I had a problem with one brand of vent window seals I bought for my 66 hardtop, they were almost 1/8" too short where they met up with the vertical bar by the lock. Left an unacceptable gap! I don't recall the brand (Texas-something?), but bought them from Ausleys Chevelle. The return wasn't a problem tho, just lots of wasted time and effort.
The second set was made by Metro, they fit much better. Thinking I bought them from Ames Pontiac when I was at Carlisle.
Note these are for 66-7. The 64-5 seals may or may not have fitment issues.