On my 69 Mustang, I cleaned out the channel of old junk, then found some thin rubber sheet that fit in the channel that allowed the window to fit also, and glued it all in with Goop adhesive. Glue in the channel, rubber, glue on top of the rubber and push the window in. The thinner you can make the adhesive the better. I don’t know about the bottom stop that limits the window, On a Mustang it’s a bracket the the window touches. I removed that and put some hose clamps around the tracks at the lower limit so it rests on the bracket and not the window. When the factory stop hits the window on the way down it pushes the window out of the track after a while. By resting it on the bracket it removes that stress.
