The pump pulley is. I had a Mioldon pump & it didn't work as well as a stock one. The radiator is 3 -core aluminum as large as I can fit in there. I didn't want to go too much smaller on the pump pulley for fear the coolant would move too fast through the engine & not absorb enough heat. Using that large a radiator prevents a mech. fan from being used is why I used the Spal fans---at Ron''s recommendation. With the car being able to idle but not run cool at speed I'm thinking it's an airflow issue as opposed to a coolant flow issue. How to fix THAT is the big question.I suppose I could try an even smaller water pump pulley & see what happens
