The '71-'74 B-body's 47.25" spring perch location does not facilitate a clean '68-'70 B-body housing swap by simply relocating the spring perches.

I recommend my '71-'72 B-body 1.25" offset spring hanger/shackle kit and a 10" wheel with 5" backspacing.

Turn the housing upside down, resting on jack-stands with a floor jack supporting the pinion. Adjust the floor jack to make the pinion point 4 degrees toward the ground. Level the new perches at 44.75" on center and weld.

This combination will bolt into any '71-'72 B-body and maintain the stock pinion angle. A Mickey Thompson Sportsman SR 28/12/15 street radial fits nicely.