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People automatically assume that in order to solve an overheating problem you have to move the coolant through faster. In reality, slowing it down will allow it to cool more. Hence fewer blades on the a/c pump.

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What???

Take a look at the drive ratios on a big block application, compare AC to non-AC.

The AC pump spins at a much higher rpm. It does not "slow down the coolant flow" in any manner. In fact, it spins faster to circulate a greater volume of coolant through the system.

The AC water pump has fewer blades to reduce cavitation because of the higher intended operating rpm of the pump.

The pump can only spin as fast as the accompanying pulley will allow.It also requires less hp to run the pump as compared to a non a/c pump.Find an old Direct Connection Performance manual,it's all in there.

Test performed on 440 source housing!
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Sorry guys... I ran these critters to the max and it looks as though the problem lies with differences in pump performance and not the housings.

I used a rig with unrestricted 1-1/2" inlets and outlets, and 1" recirc lines that let the pumps flow to the physical limits of the housings. The housings seem to peak out at about 40 gallons per minute (a flow rate your vehicle will never see due to restrictions in the radiator, thermostat, engine block, hoses, etc). Trying to push the flow rates harder than this resulted in a lot of.... well for lack of a better understood term... Bucking. This information is just trivia of course, but still interesting to note.

That said... I ran the 2 pumps that I had (the stock 8 blade Mopar & 440 source HV unit) on the 3 housings that I had ( the 2 stock Mopar styles {Left & Right}, and the "restricted" 440 source unit), and in each and every case the pumps flowed the same irregardless of the housing they were mounted on. In other words, the stock Mopar pump flowed better than the 440 pump, but it still flowed the same irregardless of the housing. Changing housings had no effect on flow rates.

Note that as the rpm's increased, the 440 source pump started to catch up with the stock Mopar unit, but in the end it was still just a little behind... but not enough to care about.

It is probably impossible to move water thru the cooling system too fast to work. Generally speaking, the faster the water flows, the more cooling it will provide.

The AC vs. non-AC Mopar water pump thing is a little interesting. The AC pumps used a smaller impeller with fewer blades and they were spun faster. I'd love to see some of the original engineering data on cooling performance. Eventually the engineers gave up on that idea and all the cars got the same water pump.

The factory engineers played some interesting games back in the 60's with water pumps and pulley ratios. The early Street Hemi motors got underdriven AC water pumps for example. That gave them the small impeller and the slowest drive ratio in an attempt to free up power. Max cooling cars got the heavy duty water pump with an overdrive pulley ratio to maximize water flow.

So if the housing, no matter whose it is,can only pass 40 gph, would the electric pumps that flow say 35 to 37 per hour, be sufficient to keep the engine cool, provided the rest of the cooling system is up to it? Would the one from Jegs that flows 55 per hour be a waste?

When all is said and done, you want to make sure you have a good high-flowing pump. That is of higher importance than the WP housing.

Other IMPORTANT factors:
The radiator
Airflow through the radiator & the Fan/shroud combination.

If these bases are covered well (from the standpoint of ability to FLOW), then other issues are very unlikely to be, well, issues!