340 running hot

Known mistake.
I could be miss informed on the topic. But it does make sense that if the coolant passes through the radiator to fast how can it get cooled down? Please explain this to me as I don't think I understand. If the engine ran cool enough before the engine was rebuilt is it possible that the cam timing could be wrong? If the owner reused the pulleys, fan blade, water pump, radiator then it would have to be ignition timing, camshaft installed incorrectly, radiator hoses clasped, clogged exhaust system. Is any of the items that I mentioned a possible cause for the problem? I don't mean to come off as a expert by no means. I'm trying to pay attention and not sound like a know it all because I'm not. I believe that I can learn different things everyday.