Hey jjgear, Do you have a router and bits as well? If not, I would suggest Erich's sub flat pack mentioned above. Here:http://www.diysoundgroup.com/subwoofer-flatpacks-2/3-sub-flat-pack.html
Tools can add up quick and unless you're gonna built more, the flat pack option is pretty nice.
Otherwise, this is close:
Panels: Volume: 3.373 ft^3
2X 19.25x19.25 - Front baffle and rear of box.
1X 19.25x19.25 - Double baffle
2X 19.25x18.5 - Top and Bottom
2X 17.75x18.5 - Sides
Bracing: Bracing Volume: 164.25 in^3
2X 2x18.5 Top to Bottom
2X 2x18.5 Fron to Back
2X 2x17.75 Side to Side
Driver Volume: 0.2
Net Volume: 3.078 ft^3
Or roll your own in whatever size you need, here: http://www.hometheatershack.com/forums/enclosure-volume-calculator/
I'd forget about the hsu amp, there is probably an undefeatable/built in filter for that particular driver in the ported alignment it's in. You can run the single mfw driver off of one channel of a Behringer iNuke1000dsp or similar amp. You'll need a high pass filter at 20Hz to protect against overexcursion, which can be accomplished within the inuke.