Dennis,
I have a 302 and 3 core radiator with stock fan in my '65 that has had occasional (not real often) overheating issues. I don't have AC, so we aren't experiencing the exact same issues. However, as I'm in the middle of another issue/change, I decided to add a supposedly more efficient water pump/thermostat from FlowKooler.com (as another person has done on his stroker). I haven't actually run it yet, but hopefully in the next few weeks. I'll keep you posted if this helps my problem.
Gene