My rebuilt 302 with redone HiPo heads from a 65 289 over heats at various times. New radiator, thermostat, hoses, high output water pump, you name it - it's new on this engine. The original 289 would also overheat as well. Is this a common thing with these SB engines? What about a three row radiator instead of the two row I now have? Any advice is welcome.