If you can't find it local;
I think I can rustle up almost everything you need, from crank to pinion of an 8.75;
less; the hump, the carpet and the underdash reverse light.
I am currently in the process of reconditioning the V8 box/2.66 low/cast-iron unit.
It Could be had in all aluminum, with a steel-bushing already installed at the front cluster-pin location.
It could be had with an in-line Mr.Gasket shifter.
I also have an overdrive unit.
I also have a stock-width 8.75 drum to drum.
It could be had with any ratio from 2.76 to 3.23, or 4.88s.
Sure-grips too, including, Tuned cone-type Sure-grips. I might even have a spool.
Also available are 340 parts.