And the answer to the wheel question is

with the 7" rims you'll want the 4" backspace, and even then you'll be close.

i have 215's on 15X7 w/ 4.25 BS running 73+ discs on my 69 and even though i'm very low, everything clears. it's close but it clears.

215's on 15x6 with 3.5BS on the same set up was very, very close and would rub sometimes at the ride height i wanted. at stock or near stock height it would probably be okay if you didn't divebomb driveways at full lock.