If I understand correctly, A/C impeller is 8 blade, but 6 blade unit is recommended for non-A/c and HP applications? I read on here that the water pump pulleys are different sizes and that they are spun at different speeds. Is this true?

I have been taking steps to cool down my hot running 360. I've got it running cool now when moving, but the temp still jumps quickly at a red light. Nearly to "H" on the stock guage on a long light. Engine then won't idle when its that hot, she's not happy sitting still. Presently running 9:1 comp, stock 318 2 row 22" rad with shroud and 5 blade viscous fan. Iron heads. 9.5" stall converter with deep pan and 2 medium sized trans coolers in series in front of the radiator. (68 B'cuda, non-a/c)

My next thoughts are (in order) 1) high flow thermostat, 2)high flow waterpump with disc on the impeller. 3) aftermarket radiator.

EDIT: I just got done reading the MP A engine book. It says use 6 blade pumps for drag racing and/or iron head and 8 blade pumps for aluminum heads and/or oval track racing if enging cooling is marginal or overheating. No mention of street use, but it sounds like an 8 blade is in order? Not that I have a lot of faith in what MP says...