You really do not have room for 2-12's ported.
You have quite a bit of power, have you considered the Solobarics? We are building a ported box for 2-10's in a truck like yours, I will let you know how it comes out. Should make HUGE bass.
Where are you getting your AlumaPro 5 farad cap from? If you have not paid for it yet, a friend of one of our techs has a 15 farad for sale. I will find out how much if you are interrested (should be cheap).
And finally, the old rule of thumb is: sealed for sound quality and ported for more bass but some sacrifice in sound quality.