16x8 = yes so far

Is that a stock 8 3/4 A-body rear end? Converted to LBP (Large Bolt Pattern)?

Or another rear end.

Stock 8 3/4 with stock axles should take max 4.5" backspacing with 8" wide rim and 225/50 tire. If LBP axles, then 4.75-5.0" (corrected) backspace. You could run 245/50 w/4.5 backspace and might need fender lipping. But 70 Duster lip might not need to.