I had cooling problems until mas28O finally helped me drop a big old 5-row radiator in(Mike, what car was that from? A Nova?). We had to cut the front frame rails to fit it in, but it worked. I had two electric fans from AutoZone hooked up two manual switches inside, and when one went out, the car still kept cool in the infamous Texas heat.
Before that big radiator, I tried my stock Z radiator with a milder 350 motor. Then when I beefed up the motor, I added an extra row to it. All I remember is that I couldn't let myself get stuck in rush-hour stop n go traffic and my car would cool fine. But every now and then I got stuck. Two electric fans blowing full blast, one pull, one push, was the only thing that kept it from boiling over.
Eventually, I got two hood louvers from a '77 or '78 Z from the junk yard and had a body shop cut holes in my '76 hood. I think that might have helped a little bit, but I don't know because that was after the big radiator swap, iirc.