Not really. You're still assuming you need some expensive, custom radiator. I cool over 400 hp made by an all iron, .060" over 340 with a $200, off the shelf Champion radiator. You shouldn't need any kind of custom radiator to cool a slant 6. Most plain old 22" 2 core radiators should be more than capable of handling most /6's, unless you've gone wild with engine modifications.
What is “terrible heat”, and what kind of driving conditions are you talking about?
You can probably skip the high flow thermostat, I’ve never had any luck with those. The high flow pump on the other hand may be a good idea. I run one, it works great with my 26” 3 core Champion radiator and Contour dual electric fans. You’ll hear different opinions on the high flow pumps, but you can pretty much disregard the whole idea of flowing water through the radiator “too fast”.
The dual electric fan set up not working as well probably had little to do with the shroud and more to do with the overall cfm flow of the fans. Generic, flat sheet metal shrouds though do give up some efficiency, but that’s a smaller effect than the cfm of the fans.
