Just out of curiousity I checked out Recaro's website. They're aftermarket selection has gotten a lot larger since I went there last time. The only problem is that the only colors they offer is black (probably not much of a problem for somebody to recover, though, I'd guess). While they're not what came in the 81 pace car, for sure, they do seem to have a large selection. Perhaps there is an option there, and all you'd have to do is track down the back seats?
Gunner