I was not looking at it that way. I was looking at it by the 275 horsepower. I know of a 273 (with .030 cast 2 barrel pistons, .030 Chrysler rings, 920 heads, Commando intake air cleaner and Prestolite distributor, Edelbrock 600, Isky E-4 solid cam, high pressure oil pump spring and a windage tray) that dyno'd at 265 horsepower. The Isky E-4 cam only has .425 lift and 260 duration. A custom solid cam should make a streetable 275 horsepower. That should work with his existing drivetrain. No mixing, no matching, no replacing, and able to last the next 50 years. This is similar to the 273 in my brothers 67 Barracuda, except he had an 8 3/4 rear with 3.23 gears and a sure grip. The engine has 300,000 miles on it, the original 904 has 400,000 miles on it, and the 8 3/4 has 350,000 miles on it. The D Dart 275 hp 273 was not street friendly, but was able to sing up to 7,000 rpm and available with 4 speed and 4.86 gears only.