I measured the window channels many years ago. I’m not sure if I have the windows handy. 1” or 1.25” sounds about right. I’m thinking more on the rear channel.
As for reglueinn, I cleaned out he channel enough to get a fair amount of glue in it. Back in the day, I used JB Weld. These days I would use DuPont Window Weld.
I’m pretty sure the coup and fastback windows were the same except for the vertical weatherstrip.
Lastly, I would sand the glass where the glue applies to the glass.