I should just give u a 1 liner reply but.... Make a plan and visit a junk yard wrecker with a tape measure.
A diff with a cast iron centre housing and pressed in axle tubes like a borg warner or salsbury are much easy hosings to shorten than a pressed steel housing used by 9" diffs. I have shorted a few of each type and I find it much easier to jig and set up a housing pressed axle tubes. If you have the tools and ability to mount up an independant rear, then an R200 or R230 (overkill) would be a great choice. You need to consider, diff ratio, I'd be suggesting a number closer to 3:1, diff type, single wheeler or limo, wheel stud pattern (will the axles need to be re-studded to suit your wheels), brake type (drum or disc, fixed or floating caliper), brake line fittings, hand brake setup, suspension hangers, spring & shocker mounts (most likely cut off your old diff, jigged and welded onto the new diff) sway bar and swaybar mounts, pinion drive, donut or uni, size and tailshaft modification, shortening the housing and axles and resplining the axles. Tack weld all the diff brackets first, do a trial fit to make sure you have a good drive shaft angle, plenty of clearance with car sitting down on the suspension, then remove and final weld.... Almost forgot... mounting the breaker. we don't want to puk that up..
Sound like something you can do?