I had fits trying to get the 350 in my 64 C10 to cool. Ultimately discovered the pulley hub on the water pump was slipping on the shaft. Stupid me, I thought the slight squeal was the alternator bearings.

BUT in the process: I now have an aluminum two-tube Summit radiator, an 18" electric fan, and 10" oil cooler. The fan is mounted in front of the radiator, and the cooler mounted below. Truck runs about 170 @ 90 degrees ambient on the road. Temp runs up as high as 190 at idle. I plan to put the fan on a thermal switch, and the oil cooler has a thermal bypass so it should do ok in winter.