About 20 years ago, in Guide to Musclecars magazine, they featured an original owner (a lady, no less!) Platinum '71 GSX. It had those Super Sport wheels (I think that's what they were called?), Stage 1, and a vinyl top. At the time, it was claimed it was the only one with a top.
If you go to
http://www.buickgsx.net, you can view the registry statistics. Unfortunately, none of the cars in the registry have a vinyl top or it just hasn't been recorded since I didn't notice any seat configuration stats either.