find a stock copper brass heavy duty /AC radiator. Or at least a HD cooling stock aftermarket. Be sure you have all the right pullies and the correct HD ,/ AC cooling water pump.
As for fan be sure you get a fan designed for AC / HD and stock shroud.
if you go with stock parts for the ENGINE and HD / AC cooling radiator you will be in good shape.
It is a basically stock engine and a manual trans to boot.
All good recommendations here for the topic starter. The only thing I see time and time again is that newly rebuilt motors seem to always run hotter. Maybe it's the aftermarket components? The change in fuel requirement? the Cam?
Anyway, if the topic starter has a good original radiator, I absolutely agree that he should give it a try before spending unnecessary money.
