The question on the Bosch 110 is if it has the needed margin above the original flow rate to satisfy this one setup

A different setup like a different engine would have its own variables of consideration

you can raise the flow rate only so much before you have to consider larger heat exchanger surface areas

 

You are correct, the Powerhouse pulley replaces two of the others. The pulleys don't need rebuilding, I'd take them off before sending a damper in for rebuilding. That will reduce your shipping cost considerably as well.
Removing the pulleys is simply removing the 4 bolts, very easy to do. Not even 5 min work. If you don't have the tools, a basic socket set will give you what you need, plus handy for other things.

 

Upgrading the coolant pump is a well known thing, the standard pump is actually somewhat marginal. Even if you don't change the pulley, upgrading the pump is a good thing to do, especially in a hot climate.