To answer your question about the interior and chassis, yes, it can help, depending on how the body is warped. I haven't built one of these Firebirds, but I did have an AMT '65 Pontiac Bonneville with a warped body. I didn't try any tricks to straighten it up. When it came time to do final assembly, I just spread the fenders and bottom edges of the doors, and the interior tub went in fine. The chassis slipped right in, and the front bumper/grille helped to tweak the front fenders into place. I hope this helps!!