Rear End Rebuild Questions

[csfields]

So I finally got done with my build and knowing that at some point I would want to change out the rear end and do some upgrade and the current rear end I have in the truck isn't exactly right but functional. So my vision was to find a donor rear end while I am out able to drive mine and go through it in the shop and be able to swap them out when ready. So this past weekend I got a free rear end out of a 72 LWB 2WD truck that had been sitting 16 years. After lifting it out of the ground using a chain and a bobcat, I got the rear end cut out and brought home. As expected the gears look they need replacing. My question is where to get the best gear set to go back stock at a resonable price and I would like to switch it over to rear disc and wondering if anyone had any input on kits. I am running 20 inch wheels so the bigger the better.