make your own ducting sir...
however just to point out... in custom pc - i saw a UUUUUBER cool (badoom tsh) heatsink - that was huge, ontop of it went 2 80mm case fans, i think it was zalman...
anyway - this one is very similar to what im trying to describe (and screwing said description up in the process):
http://www.overclockers.co.uk/showpr...=57&subcat=821
you could in theory keep the cpu fan....