I'd say just get wheels from brad. (baggedtaco)
Alot of people have done the conversion. IMO they never come out looking quite right. Mustang wheel offset usually...... isn't ideal.
So if you get wheels from brad, and want bigger brakes, just buy the calipers and brackets and rotors for the cobra. 50 doll's to redrill the rotors and it all bolts right on the mark. You'd prob save yourself bout 500 bones also.