That's only about 1800cuft and even a Hsu STF-2 should be able to handle it. Are you sure that's the entire space? Anyway the sub that I've been considering for a just slightly larger room is an eD A5s-300. I'm space (especially depth) constrained and a compact sealed design seems like the solution to my situation.
Model : A5s-300 Subwoofer $550
Subwoofer Driver Size : 12" x 1
Power : 500W
Dimensions : W - 15.5", H - 15.5", D - 17.25"
Weight : 69lbs
However if you have the money an A7s-650 should do the trick nicely.
A7s - 650 Subwoofer $1950
Subwoofer Driver Size : 13" x 2
Power : 1300 Watts RMS
Dimensions : W - 16", H - 38", D - 16"
Frequency Response : 16-100Hz
Weight : 215 Lbs