Bob, the brakes are probably going to need to be gone through front to back.
I started out just needing a master cylender and ended up replacing everything but my rear slaves and the shoes. You'll want to take it all apart and clean it up, odds are the inside of each wheel cylender is pitted with rust, as well as the lines themselves (the one across my rear axle was about as strong as a soda straw!). Just good to plan on redoing it all on something this old, and Napa stocks pretty much everything you'll need.

Do you have a brake booster under there as well?

1956 GMC 370 dump " 'Tater "
1970 VW Volksrod "the Black Bomber"
2007 Chevy Avalanche
2020 Jeep Cherokee Trailhawk,
2005 Harley Davidson FLHTCUI

I dig all cars, old and new, whether they were hammered out of American iron, German steel, or Japanese tin cans. Being unable to appreciate them all is missing out on a world of great things.
But thats just MY opinion! :P