Dad's working on one right now. It's a 65 Plymouth that's altered the same as the factory cars (10 front, 15 rear), only he's using a narrowed A-100 front axle. It's easier than relocating the K member and factory suspension.

Rear of the car was simple. Drill out the factory welds, cut out the section of floor right behind the front seats, and slide everything forward. He cut right through the frame rails and trunk floor right int he center of the trunk, and spliced in sections of frame and floor pan to fill the gap. That way, the factory frame rails, trunk floor, and bumper mount/cross member are still in place in the rear. Still have the cage work to do, but it's coming along.

The Blown 392 is finished, just need to get the car ready for it.