Guy,s with a B Body rear end...Questions

I have 15x8 rims with a custom backspace of 4 5/8 which was the max they would do on that particular wheel and have 295-50-15s on those. The 15x10 rims I mount the 10.5 x 29.5 slicks on have a 6 inch backspace. The wheel house is very close on width and the opening has to be modified for that diameter. This is on a 75 Duster that has no tub work done yet.....