Bryan. I looked at a few of the parts I have lying about. I have a couple sets of old OEM weatherstipping I hung onto for some odd reason, and it actually came in handy (10 years later!)! It fits nicely to to the curve of the rear rails. I tested on a 65, 67 and 68, all fit the same. So it does not appear that the curvature of the rear rail changes 65-68, based on a miniscule sample of parts.
I then looked at the quarter window. I do have a disassembled '68 coupe I am working on and the trim (windows completely disassembled for restoration) does exactly what you show. I could only hold the trim up against my convertible but tight top and bottom and a 1/8"-ish gap in the middle. What that means, I do not know as I am unsure how it may relate to a 65-66. But as I had the parts handy....
As for the frame-to-weatherstrip gaps, the intermediate rail weatherstrip, on my samples (years as above), extended long over both ends. A small amount at the front and a bit more at the rear, obviously variable due to the oval holes.