Finally Got My Dart

Consider just "fixing what is there." Find out what brakes are on it. Is this an original 340 car? Then it should have come with decent brakes. If that is what it has, AKA the brakes native to a 340 car you should be able to get them working well. If it has drums, they might be worn out, not just rough, but worn too large (or turned too large) and so the shoes don't fit right. If you are not going to race it or drive it hard "a lot" that might be a better "fix."