Sorry for the delay. The back corner is terrible. Pulling it tighter will pull the windlace out of the channel. Adding more material to the corner makes it worse.
I got my material from Classic parts and agree that the “bulb” is longer than original. Wish I had gone to Restoration Specialties. Over the years (and 3 trucks) I have purchased a lot of rubber parts and pieces from them. Not sure what I am going to do now as I still have the passenger side to do.