Andrew, if I was going to do this I would *ahem* base my chassis on the round tube CR. People who have been to Shelby HQ and seen a current-day chassis in fabrication know why. Clearly Ian spent some time there!
Buy a kirkham body and alter the chassis design as required to fit it.
But, I wouldnt do this because why? It's not really scratch build if you're basing it on some other chassis and buying a body. If you just want to build another Cobra that is not a pace, get a new CR. If you cant get a CR for some reason, I have a tape measure as per first paragraph.
