The 250 has a 7 main bearing crankshaft and stronger connecting rods and bigger wrist pins than a 216 or a 235. It's also got lighter weight pistons than the earlier engines. 3K RPM or more won't hurt it at all. I'd think a 3.08 with normal-size tires will be a good highway cruiser, but it will be a bit too high for load hauling or towing. A 3.30 to 3.50 ratio would be better if you plan to do more truck stuff than cruising to a tailgate party somewhere.
Jerry

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