rear disc brakes on 8 3/4

If your trying to keep the 15 inch rims then all the rotors bigger then the mustang 10.7 will not fit.
Just a heads up for those trying to keep the 15 inch rims.

You sure? Because the 11.75" B/R body rotors and calipers work with a 15" rim in the front. It would come down to caliper clearance not rotor clearance.