Just to add to your confusion, my last 69 Barracuda FB I ran 275/60/15 TA's on a 15x7 rally wheel with
4" BS. 8-3/4 10" drums on SuperStock springs. Nothing hit or rubbed. It's that 8" wide rim that causes
problems with fit.
I ran this combo for the last 10 of the 12 years I owned the car and the guy who I sold it to is still running
that combo.
I now have a 1968 Barracuda convertible 318/904 and I'll be looking at wheels for it too.