I believe the stovebolt sixes were horsepower rated at around 3600 RPM, so I'm pretty sure the factory wouldn't have done dyno testing at engine speeds that would destroy them. They're pretty much self-limiting on top speed with the carburetor, intake manifold, and port design in the head, so people who get a case of the vapors when the speed exceeds 2500 or so have another thousand RPM to work with. The big rigs with governors on them would run wide open all day at 3K+ RPM, hauling heavy loads. That's something few, if any stovebolters will ever do. Keep the rod bearing clearances in the ball park and change the oil regularly, and these old engines will take a huge amount of that kind of treatment. I ran a 1958 DelRay 2-door coupe with a 235, a 3 speed, and a 3.70 rear end and 14" tires 80 MPH frequently. The engine finally developed a rod knock, but it took a couple of years of abuse to do it.
Jerry
