It may not be, but, if you look at the two charts the differences in the early hemi were probably aluminum vs cast iron intakes and water pumps. Most of the other numbers are right in line.
Ya, I noticed that a lot of the other numbers matched. It's hard to believe that the intake and water pump would make that much of a difference though.
For that matter, the Charger could have held a 426 Hemi and look at the weight on it! I imagine it'd be tough to use any of those heavy motors in a road course car.
