Chevyguy,
If the clutch and pressure plate had been upgraded, then yes, it will in fact bolt up to your mustang with no problem. And the Tranny should fit just fine also. I upgraded my clutch and pressure plate to the 10.5 inch, I think this is a common thing to do. And also, the rear should be a 7.5, not something you would want to put in your car, although it also will bolt up cleanly.
But you know, I bought an 8.8 rear for my '85, and have been waiting for the 7.5 to fail, so I can put it in. I've been waiting a couple years now, and it has taken all the abuse I've given it.
------------------
See my
1985 Mustang GT