Agreed. Looking at them, I don't see where the MP unit would move more air than a stock mopar 7 blade unit, but I suppose it depends on which fan you compare it against. Mopar did have some pretty wimpy fans on some cars. Sure, they move a lot more air than most aftermarket performance fans, especially flex units, but looking at the massive 7 blade, fixed angle, thermal clutch, a/c units off an early to mid 70s a/c equiped big block, they move some serious air.
Back in my oval track days, we used the fixed pitch, non clutch, 7 blade mopar fans to cool our cars irregardless of engine make simply because they move huge amounts of air.