We boxed it back to slightly past the firewall with 3/16 plate. When I grafted on the Camaro clip, I narrowed the rear of the clip and widened the truck frame (about 3 inches each) until they mated. Then after welding them together we boxed everything from the lower A arm mount back to the cab.
http://img.photobucket.com/albums/v518/Blacktailer/IMG_4813.jpg
http://img.photobucket.com/albums/v518/Blacktailer/IMG_4891.jpg
http://img.photobucket.com/albums/v518/Blacktailer/IMG_4895.jpg

http://smg.photobucket.com/albums/v518/Blacktailer/1949%20Chevy/