lots of people (including myself) have or will put a 8.8 in their classic mustangs. it just takes a little fabrication, but nothing too difficult. i bought one that came from a 99 explorer. factory 3.73's, disk brakes, and traction lock. can't beat that deal for $400...
mustang steve sells adapter brackets to use SN95 brakes on a classic. he makes great parts!
1968 Gulfstream Aqua Fastback 289::T5::8.8