I've heard about guys removing waterpump vanes also, but only on the early V8's that are open systems without thermostats or other restrictors. On 48 and up truck motors it shouldn't be necessary - that's what thermostats do.
I had an overheating problem that developed recently. I couldn't keep coolant in the system. Pulling the thermostats allowed me to get home, but I kept having to add coolant. I pulled the heads and found a cracked block on cylinder #6 into the intake valve. A compression check showed that cylinder to have zero to 10 psi.
I'd check compression first to see if something major is going on inside the engine.
Then check timing, fuel settings, etc.
These trucks were built with oversize radiators and should be more than adequate for the type of driving you're doing. Keep looking for something else that's causing you to overheat. Think about the symptoms you have and a pattern will develop. There has to be a reason. Good luck. Tim