I really like the setup you have there. It's unique and makes good logical use of space. If you decide to roll with this arrangement remember to have the fans blowing the right direction so that the hot coolant is returning to rad#2 (the one that's sucking warm air), then going to rad#1 (the one sucking in fresh air). There's more of a consistent temperature delta that way, I only thought of it because it's important for GTXs. What you have there is kinda like a mega 2-part GTX.

As for how to mount the pumps and stuff, I will shoot you a PM in a while for your consideration.