If I replace the stock water pump inmy 1980 C3 with this one, will this make a big difference in the engine temps?

water pump

Don't know what pump you want to use but you need to stay with the same flow. what size is your engine, what year. need more info.

Aluminum will disapate heat and a little higher flow will not hurt. The Edlebrock is a good pump and should work fine for you.