I'd design your own ported box based upon online specs and recommendations. With this, you can decide what your goals are for this subwoofer application. Whether it may be rock music, hip-hop, c&s, or just overall musically sound. The design you were originally looking at was that of what many refer to as a "burp box." A design made to match the subwoofers specs in which you would, simply put, be able to play a VERY limited range of notes and be able to achieve a greater level of sound pressure than you would in a typical application. Music would sound horrible and with the lack of cone control on music as opposed to the tones that it was developed for, it would suffer form mechanical failure quite easily...
What music do you listen to? Are you looking to play any chopped and screwed/ LOW music? Are you looking to compete?
If you can answer a few questions I wouldn't mind getting some box dimensions for you.
And for a first box of the sort, I would recommend a regular slot port made from the mdf itself. Those design plans implement the use of round ports. (pvc, aero)