another disc brake conversion question

 is it possable to use a disc brake set up of a 76 mattador & fit it to my 65 american . 

The only issue is cost of replacement rotors. All pre 79 AMC rotors are hard to find and relatively expensive, $100+ each.  All 75-76 AMCs used big Bendix calipers  (3.1" caliper piston) and big bearing spindles and rotors. Matador used those through 78, but all others changed to a 2.6" piston caliper. 77-78 small cars used the big bearing spindle and a thinner rotor, 79+ changed to the smaller bearings used on every other AMC (including drums) and kept the thinner rotor. By thinner I just mean the space between braking surfaces, the surfaces themselves were as thick as always. The wider cooling slots theoretically mean the rotors cool better, but unless you're road racing it doesn't matter.