Yeah, even 5.5" BS wheels won't fix that spacing. Those are "Pony" wheels that came standard on 91-93 Mustang GTs and were optional on 5.0 LXs.
The '87-88 TurboCoupe rear is a Traction-Lok 8.8" with disc brakes and it is also 61" wide. It is/was a popular swap for Fox3 Mustangs, but makes the wheels stick out. Interestingly, only the axles make it wider. The "easy" way to narrow it was to install the shorter Mustang axles and either flip or modify (I forgot which) the caliper brackets. The '87-88 TC rear also came with either 3.55 gears or 3.73s.
I have read only speculation that the earlier 7.5" drum rear can be narrowed in a similar fashion.
This interests me! does anyone remember someone using a Turbo coupe rear end in a pinto? i dont mind a little wheel spacing. this would work perfectly as i have an entire donor car, and that rear should take the power i want to generate, without grenading. Ive been looking around to see if i can find anyones swap in the archives and everything, but ive come up empty.
Thanks so much for all of the help and info!
I corrected my previous post. The rear end in your '85 'Bird is 7.5", not 7.25.
Regardless, I wouldn't invest work involved with using the 7.5" (I know it's really tempting because it's
right there) if your ultimate goal is 400hp, especially if any hard launches are planned. The 7.5 will live a lot longer under a lightweight Pinto that it would under a 3400lb 'Bird with the same power, but I don't know what the limits are.
Do it once, do it right, and do it with an 8" or larger rear end. Get the 8.8" T-Lok out of an '87-93 5.0 Mustang if you want a project. The gears will be 2.73-3.08, but it should also be the right 57" drum-to-drum width for a Pinto/early Mustang.