73-76 A-Body Offset

If you want the rims/tires to tuck under the fenders and not "stick out" too bad, you'll need rims that give 2" or less on the front side (ie a 5" rim with 3.5" back spacing leaving 1.5" on the front side). I have the same set up, 73+ LBP discs with Firm Feel tubular uppers and run a 15x3.5" Weld Draglite with 1.375 backspacing and it looks decent. Still a little too far out to the fenders IMO. I'm thinking of changing to what I mentioned above a 5" Draglite with 3.5" backspacing to help pull them in a touch more 1/2" or so. Tough though because the conversion does push the track width out considerably.

That being said, I've run a 15x7 cop wheel with 4.25" backspacing and a 225/70/15 tire and it fit but rubbed at full lock backing up a bit. That was a temp combo tho and it was pushed out to the fender lips quite a bit. It was wider than my rear track width too, which I'm also trying to avoid, but again it's tough because I like my rears inward a bit too not sticking out or right on the quarter lips! If you like the 70's stink but stance and fatties sticking out past the qtr lips you won't have an issue there!