15x7 5 on 4.5 with 4.5-5 inch backspacing

anyone ever heard of such a monster? in putting an M-body 8.25 axle in my early-a, and it has .72 inches approx more per side than an a-body axle. im trying not to go the shorten-the-axle route if i can. I do know that a 15x7 with 4 inch backspacing fits like a glove on factory setups, so i could probably get away with a 4.5 inch backspace. Point in question, does anyone know of a manufacturer that makes such a thing? or someone who could build something like this? Im evidently not very savvy on finding anything as of yet....