Box design ?'s

Hi, I just got a SPL of 138.3 at a local db drag and show and i'm wanting a box to boost my numbers in to the mid 140's that wold be enough to compete around here. I have talked to a lot of shops and I've gotten a few ideas that I need advice on. This is my box as is http://www.cardomain.com/ride/2015567/2

I want to keep the shape but make it taller and bigger at the base. I have a very nice hard hitting bass and I want to keep it. First the wood is 12" x 1"  thick black walnut for the new box, is this acceptable? Second....I thinking about ports that can be sealed off when not in use so I can get the sound when i'm not compeating. Can this be done? The new subs will be 15W3v2's after I get my setup sold off so im going to do a JL styling. I thought about ports that are shaped like the logos. I can get port volume with them but will they sound normal? Any help will be great.

I am not too keen on the idea of walnut. That is a very dense wood and is probably not suited for an acoustic application. Stick with MDF and apply some walnut veneer if you are in to the walnut look.

Second, the idea of switching between a sealed and ported box is not going to happen. The internal volume for a sealed box will be different from that of a ported box and it just won't happen. Either go ported or go sealed.