Going back to the hacking in an LGA775 heat sink, this one has the needed attributes, if one could create a mounting adapter on which to screw it in securely.

XP-90



Also, the Enzotech Ultra-X, although it's a little trickier, since the heat pipes should maybe be facing away from the case fan, and therefore the heatsink may stick too far into the middle of the case. And the height just barely clears.



And the OCZ Tempest