Hey Z,
I read the feedback section on Newegg and the person who used the Antec Kuhler H20 620 removed the top mounted 180mm fan, made or bought a bracket to take the place of that fan so he/she could attach the Antec Kuhler fan to it. Although a 180mm to 120mm bracket would be hard to find, you could easily dremel a Bitspower 200mm to 140/120mm adapter (
Link) to work.
Edit: I would presume that the aforementioned owner configured to Antec Kuhler fans (Push/Pull) to vent
out of the case instead on into the case.