Rear tires- 225-60-15 on 4-1/4 backspace?

My car's almost out of paint & have to find some wheels-tires soon. Car is a 65 Valiant with stock wheel wells & will have level springs. Rear is an 8-3/4 with 10" B-body drums & backing plates (large bolt pattern). My plan was to use 225-60-15 tires with steel wheels & Valiant dog dishes. Had some 7" truck wheels with 5" backspace & these won't work (too close on inside). My plan was to use 6" wheels with the right backspace. To me it looked like 4" backspace would be about right but doesn't look like mopar ever made such a wheel. Common backspace is 4-1/4"- anyone ever try this? If this would work it would save a couple hunded bucks.