Check this case out:
http://www.newegg.com/app/Showimage....112-073-05.JPG
Lian-Li I think has done a real dandy one here. Not only is it aluminum and sealed up for quiet, but the layout is completely reversed.
As you can see in the photo, the motherboard mounts on the other side, upside down compared to other cases. This would let you cool your CPU with H20 very well, as the CPU is not sitting high above where pumps usually go. And the obvious spot for the radiator would be about three inches from the waterblock. Pretty tight.