Can anyone tell me whats a good hi flow manchanial water pump to run?

I have run both Edelbrock and Stewart in the long and short design with excellent results.
Remember that the whole cooling system must be looked at with increased flow to get the added cooling you are looking for.
You may also need to increase the size, number of cross tube rows of the radiator depending on the type of material the radiator is made of (brass or aluminum). The total area is very important when dealing with increased flow rates to allow enough dwell time for the liquid to exchange the maximum amount of heat to air.
A good radiator shop or supplier should be able to give you guidelines for radiator selection matched to your engines needs.
The hoses must be in good shape and the lower hose should always have a form spring in it to prevent collapsing at higher draw rates.
Hope some of this helps.

The first poster has made some great recommendations on pumps. I have tested the Tuffstuff, Edelbrock and Stewart pumps. All are very good and do what they say they will. The TuffStuffs edge out the rest in idle coolant flow tho....just a tad. The Edelbrocks are a bit pricey as well.

I like the Tuffstuffs because I can get chrome and the bodies of the pumps are shaped for a better looking design. The beefy front bearing design is great too. You can order TuffStuffs from www.conceptonepulleys.com (http://www.conceptonepulleys.com) direct. They stock some of the part numbers.

If replacing a radiator only go with a quality aluminum design. Copper/brass/solder radiators are considered obsolete and alum replacements can look just like the originals. The alum ones will out perform the copper ones as well in most cases about 20 to 35% more cooling ability. This is due to two inherent things, larger tubes and more shear fin/cooling area. I would take a long hard look at PRC from www.streetrodstuff.com (http://www.streetrodstuff.com) for a quality product.