Correct wheel offset and a happy front-end

Think your right on the stock Rally wheel being about about 3-3/8" B.S.
If your staying with 5-1/2" wide I would use the stock B.S. too at least on the front.

Or for 6" wide use a 3-5/8" B.S.

1/4" more or less B.S. probably no big deal on either wheel above on the front of an A body