grendi

I ended up going on the conservative side with a 235/60 on the front. If there's enough room I will change to a 245 later on. Here's how they turned out

My understanding is because an 8 inch wheel has an overall width of 9 inches. The 8 inches is measured where the tire bead is located. Half of 9 is 4-1/2.

Set your priorities. I did that 30 years ago, and still working on items.  Brakes and steering first.  Some of the prices and items seem way out of line.   Get it driving safely first, and then work on the smaller items.  Repair things as they break. 

If you are seriously considering having this shop do anything on your car, I strongly suggest they give you a separate price for every single item AND the exact brand and part number for each pat and the exact labor costs. The labor could be bulked together where several items in the same area are being changed at the same time like the front suspension. Then post that info and we can tell you for certain if you are getting hosed or not, but from what it looks like, you may very well be.
 

Make sure you don't buy cheap chinese UCA, I got the scott drake 4-rivet ones after one of my china crap UCAs locked up after 2 years and so far, they work.
If I would buy today, I might also consider dynacorn #3631JL UCAs

Here's my take - some of that may be reasonable and some of it definitely is not.  For instance, it's definitely not a good recommendation to put in performance suspension & handling for $5K.  That's NOT mandatory.  You can get new stock UCA's for lass than $50 per side (that's a lot cheaper than $350/side).
Don't put in 620lb springs up front unless you want it to ride like a covered wagon.  I think stock springs are 300 lb/in.  Don't lower it, but instead:   The top 3 upgrades for front suspension improvement are:
Redrill your shock towers to do the "Shelby/Arning drop" (if not already done) with new UCA's ($20 template + $100 for both UCA's) Put in a 1in" sway bar.  (best bang for the buck I think and makes the car safer to drive) $140 New KYB Gas Adjust shocks (Maybe $100 for both) After that, you'll need Tie rod bushings ($40ish), stock perches ($40), new spring seats ($10), some Tie-rod work
So that's like $400, and it will drive fine (not like a racecar, but you won't shatter your teeth going over the railroad tracks either)
On the rear, I would not buy new springs unless they can show you they are bent or ruined.  Just New KYB gas adjust shocks and see how it is ($100), maybe new leaf spring bushings if she's rattly.  Since there are traction bars, this will be more work.
So that's maybe $200 on the rear, and most all the big stuck on suspension for like $600-$700 in parts.  If you do this work yourself (only thing really dangerous in compressing front springs).  If you want to pay to have this done, $1500 is probably not outrageous, but I wouldn't buy new leafs. if they say they are "shot" make them show you how. 
Brakes are most important:
replace all the rubber brake lines, 3x maybe ~$50 each.  The following statement however - makes NO SENSE to me: "Found rear brakes contaminated with rear axle gear oil."  I have no idea how this could happen.  Sound like BS to me, and I would ask about it.  These systems are not connected, and I can't see how they could be thru parts failure, so I call BS.  Get a new drivers drum if you can't find someone to machine it.  New pads (cheap) and get new rear cylinders (cheap).  My brake backing plates are grooved some, but still work ok - weld and remachine is a fair bit of expensive work, and I'd try it without doing that.
They don't mention the brake distribution block or the proportioning valve.  The prop valve should be taken off and have a new seal kit put it - virtual certainty it needs that ($35 for parts).
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Engine:  That's an expensive radiator.  I bought a 3-row copper for about $350.  You can get a thermostat for $5,  you probably don't need a fuel pipe - I wouldn't do that.  If you flush out the fuel tank, there is no need to move the fuel filter ahead of the fuel pump (non stock).  New rubber connections ($10), New fuel pump $30, new filter $5.  That's all that's required.
If they can show you the leaks on the manifold you should fix it.  And you can look for this yourself, by simply wiping off the front and back and driving it around.  If it's leaking oil you should be able to see it.  personally, I don't need to remove the Ac compressor to work on the intake so - my opinion - not required.
Your oil pan probably is leaking.  Do you need to spend $1000 to fix it?  NO.  This is a hard job to get the old one off and put on a new one that doesn't leak, but honestly, you can keep the oil filled while you save some $'s to have it fixed later for cheaper than that.
Fix the motor mounts.  If they are original, they probably are cracked.  $320 seems like an ok price to do that.  Engine balancer MAY be needed.- if you can't get it to run.  But if it runs/timing is OK, I'd do this later.
For the love of God, do the all the AC/PS/alternator/fan belts yourself - any person driving a 69 oughta be able to do the belts.
No idea on the improvised trans inspection plate, but it's probably fine (it's a piece of sheet metal to keep crap out of the flex-plate starter engage area).  look at it yourself and see how bad it is.
Trans mount is good chance it is bad.  $125 seems reasonable
I'd note the rear axle seals as something to watch, and do them later.  That alone is like $300.
buy your own heater hoses. $340 is outrageous unless he is putting Stainless braid on them.
Elec:
I don't know what he means "seat plugs" but they are dang expensive.  Fix the electrical that's broken and nothing else.  he's only giving you an AC diagnosis, which means there is another $1500 of cost to get the AC going probably.  Can wait.  Two windows at 60mph is usually okay for a lot of the US.
Body:
If the roof drip rails are leaking, that can allow body rust which you don't want.  you are looking at a lot of cost that may affect the paint.  so this is expensive.  Depending on the quality level of your paint, this may or may not be worth it.  Just do whatever to avoid rust.
OMG - do NOT spend $600 on the damn clock - buy a wrist watch!  $35!!!  worst case - pull it yourself and mail it off to be fixed.
Dash: LED light kit and printed circuit panel is all you need.  your fuel gauge either works or doesn't.  If it doesn't, I would change the sender in the tank for $30, and not buy a new gauge (which is probably fine, but inaccurate - they all are BTW).
Steering wheel can probably wait at $1250!!! Good lord!. 
Fix the windows.  those mechanisms probably need an overhaul - they are cheap systems, and if not adjusted properly, can bind and be really frustrating.
UGH.  That's a lot of stuff.  I'm not a fan of having other dudes do my car work, and so I don't know about labor costs.  Anything over $100hr is questionable.  $80 may be reasonable.  My costs above are for parts, not labor (all of mine is free, so I on'y see parts costs).
This stuff is not that hard to fix yourself.  It just takes time.  If you have more $ than time - this shop may not be that bad, but there is some questionable stuff  in here - other stuff looks reasonable.  it's a mixed bag.  
Good luck.
 

This should help
https://www.mustangdepot.com/graphics/tirefitmentguide69-70.pdf
Also, my 15x10s detailed here ...
 

that is odd for moog, however, all their stuff is made overseas now as far as i know, but they have a budget line and a higher end line and the higher end line is the only thing i buy when i use their parts.
 

As far as I know, the 70 coupe quarter window trim that holds the weather strip is not reproduced and you have to find a used glass with the trim.
There is a good video at west coast cougars web site that explains the differences in windows between 69 and 70, glued and not glued glass. The video is about 42 minutes long and explains how to do a lot of stuff related to the door glass and at the end of the video he explains the differences between door glass between 69 and 70 Cougar (including the Mustang glass).
 

looks like they might have them
https://secure.cougarpartscatalog.com/store/p/15794-Moulding-/-Trim-Vertical-Door-Glass-To-Quarter-Glass-Driver-Side-Grade-A-Used-1970-Mercury-Cougar-/-1970-Ford-Mustang.html?attribs=79
https://secure.cougarpartscatalog.com/70qglasstrimps.html?attribs=79

As a general rule, long stroke motors make torque, short stroke motors rev and make horsepower. The entertaining phrase to describe the difference between torque and horsepower is....Horsepower determines how fast you are going when you hit the wall, Torque is how far you push the wall after you hit it.
 
Side oiler 427s just had an oil channel in the side of the block which you can see from the outside, a separate dedicated feed that re-routed oil to the mains first, then the cam and valvetrain, the top oiler routed oil to the cam and valvetrain first, then the mains. I imagine it addressed spun bearing failures in racing applications. If you want to be an FE expert, buy this:
 
https://www.cartechbooks.com/how-to-build-max-performance-ford-fe-engines.html

I've been driving the car around for a few days and it's better, guess I'm getting around 10-12 now.  At least I'm not seeing the needle move when I put my foot down.

if your swapping the carb, and your looking for the best mpg and power, you might look at the one of those throttle body style self tuning fuel injection systems.

Are you converting the odometer readings to match the fuel? 
Mph to meters?
kilo? To gallons
If not stored in a garage at night, may try to see if it improves with a locking gas cap
And my funny for the day..maybe be leaking from the carb overflow tube from being inverted, down under 
Back in the day in my HS years and money was tight, I put a 4x2,carb adapt and 2.85? gears  in the car, mileage was great. Now mpg are irrelevant to me, all the stares and thumbs up make that thought go away

This may be due to poor/cheap "new" repro parts.  I have been amazed at how many parts you can get for these cars at really inexpensive prices.  Unfortunately, I think the competition for lowest price drives some places to deliver substandard equipment.  So in more cases that I ever expected, I found the "new parts" were fine when I brought them, but they wear out super fast, or don't work as well as originals.  I wonder if you inadvertently bought inexpensive ball joints when you put them in, and they just weren't a good product?  Makes me wanna go check mine - they have about 3K on them now...

i did this on both my cars i can recommend it, even if you have to replace the brand new mirror glass of a new racing style mirror.

I think you have to buy the entire mirror. Don't think they make just the internals. One thing I did that you may like is the convex mirror on the passenger side.
https://www.npdlink.com/store/products/glass_assy_outside_racing_mirror_convex-183515-1.html

Afternoon Folks. Happy Memorial Day Weekend. I was able to have my front end aligned this morning at a Ford Dealership. The fellah that does the alignments comes with high regards so I thought that I would try him. We spent 3 hours on her and worked at getting it right. In the end she needed shims added to the Upper Control Arms. I measured them to be .110" thick. I had no idea how involved aligning this car was. Next up is to buy new tires and keep an eye on the wear on the tires. I look forward to having this issue behind me. No worn, loose or broken parts.

before we give any suggestions, we should first know some basics, like:
what is the current size of your rims what is the current size of your tires how accurate is the speedometer with the current tire size are you planing to use the current rims or go with another size how is this car going to be driven (street, track, weather ...)

We normally run a 18x9 with a 5.5 backspace if we're not going to tub it. The 275 fits great. 

Gees I wish my wife got that excited about buying cars. All I get told is that I have too many! ha