There were some aftermarket 5 blade fans available in the 60's, but I haven't seen any since. For more fan you just about have to either go with the flex fan or add on an electric. But, if the engine runs hot at speed, more fan won't help a bit. On your heater hose, mine has a shut off valve for the summer, so blocking them off should be okay. However, I was always told to loop the hose because that's your bypass when your thermostat is closed.
Is your radiator a 3 row or 4 row? And what was your old one? I don't know enough about the wartime trucks. If you went from a 4 row to 3, you won't get as much cooling. I understand about some areas where the radiator shops are unreasonable. Fort Worth was like that, cost about twice as much as here in Wichita. Another check is to open the drain on the side of the block. If coolant doesn't come out or is very slow, take some wire and start cleaning. Then flush the block. It might help.
