Check with the guys at Classic9. They do terrific work and are highly regarded in the Porsche world.
Porsche Interior Restoration Leather Craftsman Classic 9 Leather
They're getting the Sport Seats from my 996 this summer and down the road I'm bringing them my 928 for a complete interior renew.
They have seat kits, or you can send them the entire seat.
http://www.classic9leathershop.com/upholstery-for-porsche-996-and-boxster-automobiles/