You asked about part numbers & where to get parts. For brakes the answer is pretty much anywhere. Every big name auto part store sells every single brake part for these cars. Many will be in stock or just a day away, pretty cheap, with a lifetime warranty. Wheel cylinders are probably $15 or less. Full sets of hardware usually under $10. Shoes are cheap. Drums almost never need replacement...just have them turned for $15 each.

Just call your favorite auto parts store, tell them year/make/model, and whatever parts you need. They'll get 'em quickly if they don't already have them on the shelf...brake parts for these cars are not rare and with few exceptions are still in full production.

If I were you, I think I'd consider just doing a full brake job if you don't know how long it's been...with all new parts. Less than $100 and a weekend project and the system will be like brand new again. A Haynes or Chilton's manual, as lousy as they are for most things, will walk you thru a brake job perfectly fine if you haven't done one before. Just do one wheel at a time, using the other side as a model for when you forget where a spring goes...