Ashdawg85,
Also owning an '85 GT, I know how hard it is to find pieces/parts for them.
For body parts, you might try Mustang Parts Specialties
www.stangparts.com I have had mixed results in dealing with them. I bought a set of original '85 seats from them. They came damaged, but they did send out repair part for them very quickly. Another order I bought from them never ever showed. So, just be careful dealing with them.
Alot of people have had good sucess with
www.texasmustang.com I have never bought from them, but looking at their site they have a bunch of stuff.
As for engine parts, that was the last year for the Carb, so don't expect alot to be out there. I was able to use new exhaust pieces for an '86 with minor alterations. And you can use an '86 and up clutch if you change the bolt pattern.
Good luck with it. If you have any specific questions, feel free to shoot me a private message.
Harry