Speaking from experience, 50+ year old window channels and regulators don't really take or hold adjustments very well. Get them close and call it a day. Having a ragtop, do you really want to drive her with the windows up!? I try not to.
1968 Impala SS
Unfortynately, here in finland it rains sometimes... 😂 😂 😂.
If i roll window all up, the window sealing, jumps off, but if i let window about 0.5cm open, sealing stays where it should be. (window brush sealing).