Tire/Wheel choice

You really need a custom 15x8 and 4 inch backspace. That will get the tire/wheel right where it needs to be but may require some trimming of the fender lip. I saw this on a duster at a show the owner told me these specs. He had the 8.25 rear. Tires were 275/60/15.

You really don’t.

If the tire and rim is where it needs to be, there should be no cutting at all. With a 15x8” and 4” of backspace the tire will get into the quarter lips unless the car sits high in the back. It might work with SS springs, but if the tire is going to fit inside the quarters that’s the wrong combo.