OK, so the 9" wide bullits have a little more backspacing. Are these an aftermarket rim? If so what brand?
I think the 6.1 backspacing would go nice with a 68-70 B-body rear end. Those are cheaper easier to find than the 65-67 B-body rear ends. And the 68-70 B-body rears are much cheaper than A-body 8 3/4 rears.
Just in the process of mocking up some 275/40/17's on my Barracuda. I'm doing the mock up with 17x8 '02 GT rims with 5.625 backspacing.