gordonr

If you believe the dash gauge is bad, you can swap your gas gauge with another gauge (oil pressure, water temperature) by swapping wires at the dash cluster connector.  The guts of the gauges themselves are identical.  Of course, the ammeter gauge is a completely different animal and uses non-fused battery powered lines. 

"When I do upgrade the '69 radio with an audio input, RCA outputs would be nice so I can add a 4-channel or 2 2-channel AMPS and better speakers.   Not looking for high power and thumping subwoofers, just a clean sounding system."
 
Your not alone, Not everyone wants a large audio foot print in their classics. I've been focusing on that exact goal recently. I did an install on a 66 mid year vette a few weeks ago with no sub system as the customer wanted his system to have a small foot print. I came up with the idea of using the center dash 6x9 speaker as a woofer only, bridged out on the rear outs of a small alpine amp set on low pass. I used a set of high end 4" mids in the kicks with super small tweeters mounted in stealth areas on the dash set on hi pass. It sounds amazing. I started on my mustang a few months ago with this goal and I finally started making time this week to get back on it. I'm using a Apline R 5.25" as my woofer in the center and made steel screw in adapters in the original door speaker holes to support 4" mids.

Bald jokes? 
The best part of this storm is that I've lost 20 pounds and my appetite.  It is hard when you're old and have to do manual labor for 8 hours in hot, humid conditions.  I got my first sleep last night that was longer than 3 hours. 

I see devices as these as a future problem to deal with. I'd pass on it.

" After a recent incident of a dancing tach, I decided to check all 3 original grounds and added a couple more.  I added a new ground from the back of the intake manifold to the firewall as well as firewall to frame."
A few things are going on here . Besides the ground providing  a  path for the ignition coil to saturate  then release  the high voltage  it is the  power "on" for the module itself to operate.  As with the conversation around the pertronics and bypassing the resistance wire because of low voltage issue  hurting the module,  a poor ground can have the same effect.  Testing electrics is testing for a difference of potential . For example  using your voltmeter on "volts DC" add attaching one lead to the negative battery terminal and the other to where your module ground was bolted. Measuring a ground point to another ground point will measure a difference  of "0" on your meter or "no difference" in a perfect circuit when cranking or running.  In your case it wont be. I would be checking your 4 gauge engine ground as it also supplies the path for your alternators charging system. The acceptable spec with engine  running with all your accessories on is .5 volts or less across your main ground. Your chassis ground can be measured the same way by moving your lead of the intake to a chassis point. Your goal is as close to 0 volts as possible as its responsible  for all the accessories on your car. 

There is another option. Use the red wire feeding the w/wiper motor.  The choke should draw 2 amps up on initial power up then drop to less than .5 amps after 5 minutes. Randy at Midlife made up a small harness to plug in between the motor and the harness with the splice  to feed the choke so no damage to the original harness. I was obsessed about not having it show.