What are the differences in cooling capability between the MP 5 blade viscous fan and this one I have here, which is a 7 blade unit, but I don't know what it came off of? Big block? Motorhome? Max cool package? I'd like to use either of these on my 408 stroker, but what is the max rpm for these, considering the clutch will be replaced with a new one. it sure seems like this 7 blade unit can move a huge amount of air.