That car is ruined. It was never structurally designed to be a convert. With the color and interior modifications it is now a parts car.
A number of years ago, I went to look at a 1965 Riv for sale in Michigan, the guy was proud that he cut the top off to make a convertible :>, I ask him to open the doors (I could see the sag). Alas poor soul, ou: the doors were jammed shut... Never knew what happened to that car Roger
That's one Buick SHOULD have built but didn't. I remember a while back seeing somewhere on the internet (can't remember where) factory pictures of a Buick 63 Riv convertible prototype. It looked great. It sticks out in my mind because it had an unusual folding top mechanism. The frame folded in towards the center of the car before stowing behind the seat. Anybody ever see those pics? You are right, that car is ruined. Just another parts car. Chris