Thank you all for your replies...and advice!.
The most common cause of heating when stopped is lack of adequate spark advance. Newer fuels burn slower and if you've installed an aftermarket carb the chances are it's a bit lean, too. That also makes it burn slower so excess heat ends up in the exhaust port instead of being turned into mechanical motion and the coolant has to take up the slack. Consider running as much timing at idle as the motor will tolerate, including switching your vacuum advance signal to full manifold vacuum. If you have air conditioning,...
Thanks, Bart. I'm running ethanol free gas, and an Edelbrock 1403 carb. From the factory, the carb is actually running rich (and getting bad mileage) so I just recently changed metering rods to 1 step leaner. It idles better and accelerates smoother. Initial timing is 10 BTDC. I'll bump up the advance and continue tuning the carb, and see how those changes work.
I don't have A/C, and already have a 3-row radiator with shroud. The current 5-blade fan sits right where it should, half in/half out.
I have one car with and one without AC, and another AC car that is disassembled but all three have the original 7-blade C6OE - G fan and thermostatic clutch.
Perfect! Thanks for the part number for the fan. But man, those guys are not cheap! $250 and up on eBay! Apparently, no one makes repro version. All the repros, like the Derale that Hemikiller recommended, are the 6-blade version and not the 7-blade. I did find repro's for the 390 7-blade fan but they're crazy expensive.
Hayden has nice dimensional drawings on their catalog, so you can see where everything will fall. If you need to adjust the position, you can do as huskinhano did in his pic and put a spacer behind the clutch flange..... Another option would be a unit from Derale, they make them in 17" through 20".
Great info in those Hayden dimension drawings! That'll be a big help. But ya, I only see 6-blade fans on the Derale website.
So I'll try the timing and vacuum porting things that Bart mentioned, and will start searching for a 7-blade fan, maybe one that needs some restoring that might be less expensive. At this point in the year, maybe I can get by till the fall and take my time over the winter searching. If not, then I'll just go with the 6-blade with a thermostatic clutch. That'll be less costly, and still be an upgrade from the fixed 5-blade and also be quieter.
Again, thank you all!!