Your post must have gotten lost in the shuffle, it happens sometimes. Do a site search and use Mustang rotors as the keyword. This has been done and discussed here using '65-'66 Mustang rotors. If memory serves, the rotors needed the wheel register machined, there were some monkeyshines with the bearings and seals, and the diameter of the rotor had to be reduced. Not sure what all was involved but it was done, it worked, and I read it here in the brakes forum.
Having said that, why don't you swap on '73-'76 disc brakes? It's a lot less work, parts are available without a second mortgage, and having owned cars with both setups the single piston sliders are much better brakes. You can sell your setup to the Resto crowd and more than pay for the swap, plus you will wind up with better brakes that give you fewer problems. Food for thought and I hope this helps.