Rockauto carries a lot of mechanical parts, you can probally get brake parts from there. I like to do the front disc swap from mid to late 70s valares/aspens. There are quite a few other cars that you can swap from. If you can find the spindles and caliper adapters, it could be done much cheaper than for 450.

I'd try searching here for info on the se rear window.

A numbers matching 318 probally wouldn't make it more valueable than swapping in a 340 or big block. Myself, I rare keep them as 318 cars.