If you go looking for a donor to pull GM buckets from, be aware of the year. At some point they started molding the foam onto the frames. I think this started with late third gen Firebirds, then migrated to fourth gen Camaros. Beyond that, I couldn't say. I pulled a pair of low-backs out of a '92 Firebird, and was horrified when I got the upholstery off. After ripping and scraping as much of the foam off as I could, there was a glue-like layer left that I used Cirtristrip to get off. Then the plastic inserts that the headrest bars slide into proved impossible to get out, and I fabricated a homemade cutting edge to slice a piece out and get them past the metal spring tabs that latch the bars. By this time I was way past feeling like an idiot. Had I known all of this I would have taken a pair of the "Star Trek" style from a '91 Camaro in the same yard. I had the recliners from it but it was gone already by this point. I did find another pair of "Star Trek" back frames, but they're pretty rusty. Not sure which I'll use.
I also like those Procars a lot. Spend a little, save a lot of BS, as usual.