[Jack21]

Just a guess on the 30% overdrive waterpump pulley on a big block.

"Typical" end use is 4,000 pound sedan, or 6,000 pound PU with air, and auto trans pumping a lot of heat at low RPM.

In this case, you're loading the engine less, and pushing more water through, so you need less overdrive to the waterpump.

Probably the 5.25 on the water pump, Edelbrock, or somebodies aftermarket high volume water pump, and good electric fan (Spal)with a dash mounted manual-on switch should keep your BB cool in beach traffic in the summer.