B body 8 3/4 into a body

That may work out good, I'm not sure of the backspacing on the Bullit wheels, but I'm sure it's alot. I have a '68 B body rear in my '68 Dart which added about 2" in width (drum to drum). I ended up using a 15x8 wheel with 6 1/2" backspacing which is just about perfect for my car.
The '66 and '67 B body rears are a fraction narrower than the 68-70 according to some charts (drum to drum). I don't see any issues with your combo.