Well, here's my take on it. Henry built those boxes to handle a max of 100 horsepower. I don't know what the torque production of the flathead was, but lets get generous and say it was 150 ft. lbs. Can you show me ANY V8 today that would only register 150 on a dyno?

I just looked up acceleration on the old 255 flathead and a 49-53 Merc would do 0-60 in about 16 seconds.