I would say you should go with something around a 152 length. Your going to gain a little bit of weight I'm sure. And your boot size just means you don't have to worry about board width, but the narrower the better. Getting a board this short though, you should be fine.
I would recommend a Capita Indoor Survival FK in a 152. Make sure it's the FK though... I wouldn't go much larger then the 152.
Another recommendation would be a Ride Machete or some other flat cambered style board.
Just stay as close to a 152 as possible.
Oh and make sure you take your time buying boots and bindings. Boots and bindings are the single most important items in your arsenal, so don't pinch pennies in that department.
"When I do good, I feel good; when I do bad, I feel bad. Thatís my religion." - Abraham Lincoln
Moral of the story: If your going to rob people, wear a diaper.