Mark,
I used the "deluxe road race" and fabricated the cut down back and cover. These are about $800 a pop plus, seat mounts, fab work, and having the covers altered. The "intermediate road race" seat is around $400 plus the above.
In retrospect, I would look at the "vintage" seat, also around $400 but no fab work. I think it's a good compromise and should bolt right in.
The seats are an issue with these cars and the Kirkey is the only thing I could find that fit and gave me the support I wanted. Also, these seats keep your butt on the floor pan.
http://www.kirkeyracing.com/
John