Typical for 40 year old windows and a badly designed switch and power system. New motors will help, but you'll also need to lube the tracks and check the guides and rollers are good. But that will still leave you with a slow and power-sapping setup which is why many rewire with relays to get similar results to more recent cars. The other parts seem to be problems or worn out before the regulators are the issue, usually.
It doesn't sound like the problem, but when I got my car the window only went half way down, got it home the next day and pulled the door trim off to find the mirror remote cable was fed through the window mechanism. The guy said it must have just started doing it. Rubbish. It would have done it every time without fail since reassembled by some clown. Easy fix, I feared the worse before that. But then replaced the motors and rewired with relays as well and they shoot up and down faster than my 10yr old GM car.
