This might be too extreme for what you want, but there was a chassis on another website I get on that was built for a 68 Dart pro mod. It was never taken down the track. He had another chassis built to certify the car to go faster. They wanted $6500.00 for chassis, all floor and tub tin work, had a $7000.00 plus rearend that went with it and some other stuff, just can't remember right off top of my head. If interested let me know and I will see what I can find on it.
I know you are looking for one to build, just thought I would throw this out there.