Ok, the box might be tight for 12's. It depends on how they measure the height, but it might be close.
Here's a copy and paste from
crutchfield for box size recommendations, for the kenwoods:
# sealed box volume: 0.6-1.5 cu. ft.
# ported box volume: 0.75-1.75 cu. ft.
You're way too large. You could probably fit 4 of those in that box.
I'm going to go back to my prior suggestion. Your dad gave you woofers as a present? He sounds like a pretty cool guy. Why not re-build your box with him, or consider building a box for 12's or 15's? You'd be surprised at how cheap it can be to do it, and you'll learn a crap load about car audio when you build it.
If you have that much air space to use, you could really run a much larger cone setup, and get more bang for your dollar by doing so.