ive got a friend that has built 3, and it is a cut and weld fab when your happy if you are changing out the OEM motor for a V8. there is no set pattern for cramming a softball into a baseball skin, its just what you can get to fit where. he uses the jaz drag seats from jegs or summit in his. as far as the firewall i use a large single piece of cardboard and trim it to fit as a pattern, then transfer that to a final piece of sheet metal.