Need box help

[dcofer]

My buddy has an '89 Silverado single cab with the bench seat and he currently has 2 JL 10w1's in a sealed truck box behind the seat. We are thinking of upgrading to a ported enclosure, and I have some ideas of what to do based on other builds, but they are generally for 8's and behind the rear seat of crew cabs (which i think is a bigger space) or in other brand single cabs. I wont be able to get the current box specs and available space until this weekend most likely but if anyone has any thoughts or pointers it would help.

The goal of the build is to get some lows into the truck, you can feel some now but not much and not too low (maybe into the mid 30's, maybe). The truck just peaks too high and though its loud it just doesn't have much range.