Welcome to the friendliest forum Kaitlyn, and congratulations on buying the best looking car ever club. As you know, 69 sportsroofs are hard to get nowadays due to their recent popularity.
Good advice from Midlife above. If you haven't already done so, many people get a Marti report
to find out a bit of info on their Mustang. It includes build dates and what parts and options your particular car was built with.
Here are a few Mustang businesses that most enthusiasts believe are the best in their field.
http://midlifeharness.com/ for wiring restoration. Randy was the first to reply to your post, is a plethora of information, and a swell guy.
http://www.chockostangclassicmustang.com/ for all things steering and brakes. I highly recommend you at some point send him your steering box for a rebuild. After 53 years it needs it. Dan and Carol are also great people to deal with.
https://opentrackerracing.com/ for all things suspension. John is also a great guy.
If you call these guys, you will be talking to the owner. Just tell them what you are planning, or ask for advice, and you will get good, solid information.
https://www.npdlink.com/ National Parts Depot (NPD) for parts.
There are several other good Mustang vendors which will be mentioned to you during your build.
Pics. We love pics here. At least I do. Especially pics of your 69 as it currently sits. We also like to know what part of the country you're from. If you don't care to list the town, a geographical location helps.
And again, welcome to the forum.