Hi Robert,
I had my 200SS seat done at Premiere Custom Upholstery just south of Butler, Pennsylvania. They copied the few scraps of original cover that I could provide them, and some pictures I got from the web. I restored the seat pan, they did the padding and the seat cover. Although it's not an exact replacement of the original, I think it looks pretty good. You can see some pictures in the 175-200 gallery. Mine is the Krylon Grey version. What was left of my original seat was so rotted we couldn't really identify the material. I had this one done in all vinyl.
Some pics you'll see show my home made seat version, which Premier covered too. I initially used that seat because my original pan was rotted beyond use. Eventually, I bought a proper pan on Ebay. You'll find two of the pics do show that restored seat.
If this upholstery job catches your interest, I can take and post more pictures of the seat. I'm sure Premiere (or one of your local shops) could do the same for you. Maybe even better, if you know what you want. I had a hard time finding good pictures of the original seats on the web. Good luck.
Gary