going to have to agree with Don, Spal is the best, the more CFM of course the better its going to cool, It will our perform and pulley mounted fan regardless of the blades. But also if it works for you in 100 degree and 110% humidity then don't waste your money in less you like the looks. As the ol saying goes if it ain't broke don't fix it.
But i can tell you one thing running 2 huffers on top of a 600 ci motor i wish i had 5 electric fans and 2 pulley fans. Running 1 blower is like running 3 A/C units in your personal driver.