I'm in the same boat.
Getting a YY-Cube and had to figure where to put the rad.
I have decided to put it in the rear on the drive Bay side.
Putting a rad above the power supply didn't sound like a good idea. If I do get a leak... don't want it dripping on the power supply.
So i decided I will move the powersupply to the top, and the Rad on the bottom. As for ducting, I thought i'd duct it from the side.
Make a composite shroud (thank you #Rotor for the how to) that is curved to draw air from the side and pass it out through the back.
This system would use 2 120mm fans to cool of the rad. the core i plan to use is the same one Ben2k is using:
core#2-304. It seems to be the best fit in the case.
I would still have one 120mm fan blowing on the Mobo side of the case. If I use aluminum frame fans like
this one it is 80CFM at 30db. I imagine it will be very quite running at 7 volts.
This idea my help..