A little tech question here:
I'm putting a 500 (508 now) Caddy engine in my '75 El Camino. I'm wondering about what it's gonna take to keep it cool. Right now I have a GM radiator that is a 4-core copper type, but I'm thinking a Be Cool aluminum type may be a better choice because of weight, and because it would be new.
Aluminum is much more efficient at cooling it seems, for less mass etc.

The brass radiator may be OK if it's in good condition. I'd try it first and see how it does.

I have found that the type of impeller on the water pump is what makes a big difference..A closed impeller like the picture... they can be found for a lower price , but 500/472 caddy vendors have them for about $100 ...NAPA use to have them for about $50...

The radiator you have should work OK as long as the fan blade is spaced half in and half out of the fan shroud looking down from the top side. A 500 cu in engine runs no hotter than a 6 cyl as long as the system holds enough coolant and water to dissapate heat. If the coolant passes too fast thru the radiator either because of flow or improper thermostat then any size engine will run too hot. Fan spacing within the shroud is most important as well as how clean the radiator is and timing is correct, thermostat is correct. What you want when you're done is an engine that gets up to temp quickly( 180, 205) and remains stable within ten degrees. An engine will get better mileage, and run cleaner at a stable 200 than at 180 degrees.