Maximum RPM for 273 64 Dart

273: Cool chart! Factory rated was 230 for a stock Commando as I recall, you're just passed that. You dyno'd a stock motor to get these numbers?
Actually (and I apologize for this quibble), but the factory rating was 235. Not that those old gross horsepower ratings were that accurate anyway. Or that production standards weren't sloppy enough that there was probably more than five hp difference between one motor and the next.