I have watched the tests three times now.
I would say the 426 Hemi is over rated by a min.of 200 hp. in other words I would say it would be much closer to the 600 hp area.
I think the FE would be closer to the 575 hp,I think it would take a huge mech. cam to even come close to the 637 area and I think it would be at a much higher rpm.