Box help?

OK i know most of you usally charge for this kind of thing but heres hoping. Within a couple of days i hope to place my order for either 2 SE 15s or 2 SX 15s and my ED nine 1. So how will i need to design to the box for the back seat of my 91 camaro. I will post up some measurment tommrow of how high,wide,and deep i can go. I've been told to go ported tuned to i think 28 hz but this is my first ported box so i have no idea how to "tune" the box to that. Btw my head unit is going to most likely be a Jvc Kd-shx700 what do u all think of those. I've found them for 250 new shipped. Welp let me know what u all think of the setup. Once again i'll post up the measurment tommrow. I do have a sealed box in the "trunk" area of a camaro but i know its no where big enought for what will be needed.

Welp I got bored and just took the measurments tonite 56wide 54 in some places.24 depther with 2 inches gap from the back of the seat. and 19' high b4 i start blockign rear view mirror view.