8 1/4 or 8 3/4 A-Body Rear End Assy. 1973 Dart Swinger

Hello. We have recently purchased a 1973 Dart Swinger. It is a Slant Six car with small 7 1/4" rear end. I am doing a V8 swap and need a larger rear end. Sure Grip is preferred but not required. Just needing whatever I can find at this point. Willing to travel within reasonable distance. Thanks.