Almost anything you buy new will likely have some sort of bolt in seat track arrangement. An E body cabin is wide enough to swallow almost any seat out there. It will simply come down to your choice in options, fit and price. These guys support a lot of classic american muscle cars and are competitively priced with a lot of options for fit;
http://www.arizenracingsports.com/ plus they can provide matching rear upholstery as well.
If you want the cheaper way to comfort and don't mind fabricating tracks, used seats from a salvage yard may be the way to go. Especially if you go to a pick and pull where you can test fit them. Typically you'll be looking at import stuff for the widest range of styles and options, although some late model stuff is decent too.
I picked up a pair of Supra seats for my project for $50. They offer three seperate lumbar support bags, adjustable back and thigh bolsters, adjustable thigh support, adjustable lay back, plus the usual tip to enter. They will need recovered to match, but not a bad deal overall.
