The 2 ported is a great idea.. And for sound quality or SQL should I say ( since that is what JBL acoustics is known for )... Don't tune over 35hz and no lower than 32hz.
BUT, there is a problem with going just 2 of these subs and that amp...
... U can only wire (2) 6ohm dvc subs to 1.5 ohm or 6ohm.
That amp is 2ohm minimal ( technically with amp rise, box rise, and the warming up of the voice coils - it MAY eventually give u a 2ohm rating or very close ( something crazy like 1.8ohm ) but I would wanna risk the amp having to be stressed playing before those instances happen..
.... Running at 4ohm, u'll be good & the amp with be running efficiently which = less stress and normal operation warmth.
Now u will be about: 360 watts under power... BUT, adding a 7volt eq and/or crossover with take that slack up & provide extra to play with.