Just another two cents worth, I have a 216 in my Chev '52 1/2 ton and have 180 grand on it and it is just starting to smoke a bit. She is getting pretty weak though. I've run her hard towing trucks back from California, Southern Utah, Omaha and all over this country in Wyoming. (I have about 30 '47-early '55 GM trucks).The only change I did when I did the rebuild, and it was a '47 engine, was getting the insert conversion. I am biased to the good old 216.