yea this will work. But imo five cubes would be better, because once you factor in displacement its going to be under four cubes. You want at lease 2 or more cubes per sub. That's just me.
I think 4.75-5 would be better too, and make REcalc say 28hz, cause that will really put you at around 30hz (lengthen port piece 2). As-is it will not **** though.