rear end
To locate an 8 1/4" rear, it will have to come out of a 73 and later car, most likely with disc brakes. Any Duster, Scamp, Valiant or Dart from 73 and later would be a possible donor. No 8 3/4" rear ever came with the LBP so if you're looking to swap an 8 3/4 in, you may end up with a bolt pattern mis-match. To check for a suregrip, either check the buildsheet if the donor car has one, or if you can jack up the car, spin the rear wheels, if they both spin the same way, it has a SG. Ratio shouldn't matter as you can always change that, the big thing is to find one.
Too bad you're so far from Michigan, I came across a bunch of cars with 8 1/4's and am going to be bringing them home as time and $$ permits!! Good luck with your search!! Geof