If you are looking for reproductions of the originals, nobody makes them. You have to locate a used set and have them recovered. There are aftermarket seats available, but they are universal fit and would have to adapted to fit your particular application.
The good news is there are several cars to get them from. 68-72 chevelle, cutlass, monte, basically any "A" body GM vehicle. They all use the same framework, I see them on ebay all the time usually go for anywhere between $200 - $350.
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