Help with bandpass box...

My friend wants me to make him a custom bandpass box for 2 12" JL Audio W3's. He has a Mercedes, and it had a built-in 10" factory sub that he removed when he got the JL's. I attached a drawing of the proposed design. The old sub hole is in purple, the plexi is light blue. Is this design possible, and if so, do I need to do any additional porting?

well as much as your drawing confuses me, I think I understand it, and that should work just fine. :)

looks like the port goes out the top ........ that should work fine. I assume the factory sub fired thru the rear deck.