I ran weld draglights 7" with 4 1/2" backset with a 245/60/15 on my 68 Dart

I had the 8 3/4 with moser axles/green bearings/large brakes,which made the whole rear wider by a 1/2"...1/4" each side

they fit perfect in the wheel tub with a 1/4" clearance at the fender lip and at the tire bulge and leaf spring( did not roll the fender lip)

i did get a 235/75/15 on the 7" with 4 1/2" BS on it once..it was very tight getting it in the wheel tub but wound up too tall for meand was a little at high speed(rear jacked up)

when i used a large bolt 7 1/4 rear axle the 4 1/2" backset with 245/60 would rub on the leafs at the tire bulge on hard turns(just enuff to scuff the riased white letters

the 68 small bolt 7 1/4 had 13" rims and never tried anything other that the stock 13x5? rim

swaped that 8 3/4 in the 85 truck and went 12" rim with the same 4 1/2" backset

mid 80s stock rims and the cop rims have a 4 1/4" backset on them,IIRC