8" wheel, 4.5 backspace with a 12" section width tire, 29.3 tall, is about it from my limited perspective.

69 gtx, stock width dana 60, SS springs, and newly replaced quarters/wheelhouses/AMD parts.
I would start somewhere in that ballpark on most cars.

On mine, 5.5 backspace would put the sidewall of the tire into the leaf spring, and 5" would be shaky/don't ever turn.
10" with 4.5 backspace would put the sidewall of the tire into the outer wheelhouse.

There is a skosh of extra space that could be utilized on the outside by using an
8.5 or 9" wheel instead of 8", but those width dimensions have both proved to be harder to find than 8".