68-71 340's make more than 275 HP. They were Factored up to 325 and higher by NHRA. My only point is to look at NHRA factored HP numbers and not advertised numbers. They are closer to comparable. If you pay attention to YR, Moper, and Perfacar, that level of machining works great on the street with no bad side effects. Few people understand what great machining will do for output (HP).