Another Radiator question

[Rufas]

I have a 1970 GMC with the original 4 core Harrison radiator. The radiator is in good shape. But the Arizona summer temps are typically between 110⁰ and 120⁰. The 4 core isn't happy idling in these temps.

So I'm considering replacing it. I've researched here and now totally confused. There are so many options brass/copper, aluminum, 2 core, 3 cure, 4 core, 5 core, fin spacing and the list goes on and on.

Fit also seems to be an issue, especially the lower rubber radiator pads. What is the best bang for the buck. I'm not crazy rich so my budget is about $500. I'm not worried about keeping the original appearance of the radiator. I just want something that works.

Who has experience with replacement radiators? What style radiator can handle the summer temps here?

TIA