One of these days I am going to tackle this issue. I have an 80s fox 8.8 and a 8.5 in a SS to reference. It won't be the first time I've had to mod a rear to fit. I plan to make relocating brackets to get 8.8 in. Brackets are already made to relocate the uppers. With 31 splines it should be as good as a 12 bolt. The best part of a B body 8.5 is you have to cut of the ends so there is no excuse not use ford bolt in ends.