I am just finishing my conversion this week. My 66 was a 6 cyl coupe that I was converting to V8. My source car for the brake conversion (not the engine)was a 77 Maveric with a V8. I swapped out the rear axel and am now doing the front disk brakes. (I obviously wanted 5 lugs all the way around not just on the front.) It has been increadibly simple compared to how hard I thought it would be. My source car had just been worked on prior to getting junked (1 week in the yard only) so it had all new rotors and brakes. Lucky me. There are several places on the web that can show you how to do it including
www.mustangsteve.com. Good luck.