I did a quick search at the JEGS site. I didnt see any hi-flow water pumps for a slant six. Anyone see or hear of any being made?

Unfortunately I think you are pretty much limited to the stock replacement option. There really isnt much left for performance parts available for the slanted dinosaur.
In reality I dont think you should have any need to go higher flow than the stocker. If you are having cooling problems I would look into getting the rest of your cooling system in tip-top shape.

For all things /6, check these guys...

http://omnipages.com/sl6_parts/parts_view.aspx

Thats what I thaught I flushed my system real good last year new hoses thermostat ect. Shes not air bound. Timing is right on. That header throwes a lot of heat even though its wraped . Maybe its time to upgeade the two core rad. I by-passed the heater core when I went through the system, its a leaker. And I never use it anyway.

take a look at this site. they should have what you are looking for. i just bought 1 for a v8. if it works it's worth the extra money. read the site . some interesting reading. i did not receive mine yet, i hope it meets his web site bosting,,,,,

http://www.waterpumpwarehouse.com/servlet/the-45360/Dodge-A100-318-V8/Detail

http://www.waterpumpwarehouse.com/servlet/Categories