My buddy runs a stock abody small bolt 8 3/4 in his early dart with 255s 4 3/8 back space. On a 15x7 Tight but it works. I’m also going to have the same set up just waiting on rims.
Actually that makes a lot of sense, although I bet those tires are real close to the springs with that backspace on a SBP rear. The distance from the wheel mount to the springs should be the same as any A-body as long as you're comparing SBP to SBP or BBP to BBP with the A-body 8 3/4 rear.
On a BBP A-body 8 3/4 with stock spring locations it's about 6" from the wheel mount back to the spring. So with a 255 being about 10" at the section, that's 1" of tire overhanging the rim. Plus a 1/2" of clearance, for about 4.5" of backspace. You can run the spring clearance tighter than a 1/2" though, and I know that people have talked about using 4.75" as the backspace for 15x7's on BBP 8 3/4's. And that would pretty much translate to 4 3/8" for a SBP rear. That makes it tight on the springs for sure, but it's always better to be a little tighter to the springs than the quarters. You can always run a thin spacer if you end up too tight to the springs, the only things you can do if you're too tight to the quarters involve bodywork.
