I did a T-5 conversion in my '67 at the beginning of the summer. It is one of the easiest driveline changes you could possible make to a car.
This article by our friends here at FORD MUSCLE was incredibly helpful to me. I used to have a few other websites also, but they are saved to my favorites on a different computer 600 miles away

. That article will basically tell you everything you need to know. In a nutshell, If your car was originally a 3 or 4 speed stick car, switching it out is just as easy as replacing a clutch. You will need to fabricate a new crossmember however. Also, there is a chance you will need to shorten your driveshaft: luckily I didn't. You could also opt to go with a hydraulic clutch setup, eliminating the z-bar, but I dont know if it warrants the $300+ kits. With my original z-bar and linkage combined with a diaphram clutch, the pedal is easier to push than most new cars I have driven. If you need help purchasing a used transmission and figuring out if you getting a v-8 one,
this article was also of great help. Hopefully this will help to point you in the right direction. If you car was originally an auto (like mine) you may have trouble finding the pedal setup and everything else, but I have to say it was probably one of the best things I've done to the car so far. Infact 2 weeks ago I drove the thing from my home in upstate NY 600 miles to Michigan. After cruising 70-75, sometimes faster, It never even saw above 2000 rpm in 5th with 3.00 gears. At 70 it held roughly 1600 the whole way, getting roughly 20 mpg with a 331 stroker motor. Its well worth the trouble. If you have any questions about the swap on some things that the article may leave out, feel free to ask me through pm or whatever, chances are I will be able to help
Will