Problem is the rods will stretch easily due to the poured babbit bearings. Yes, they will turn 4,000 rpm and go 90, but you will shorten the life of the engine. 45 to 50 max for highway driving. Lumber I worked at in high school had an orange 52 1/2 ton, one day I decided to see how fast she would go. Had her at 90 (top of the speedo). She didn't want to stay between the ditches, and my drafting teacher saw me. The next dad he said he saw an orange blur flying down the road...
