Have you spent some time here?
http://67-72chevytrucks.com/vboard/f...play.php?f=199
I know that "Sharpie" gets burbs every once in a while, and is a great guy to do business with. If he doesn't have the seat, he may have a recommendation on where to look for you in your area??
Seats are a PITA to find and purchase, since they are so large most do not want to hassle shipping them.
Good luck!