150w or 250w hps/mh digital ballast

Im setting up a fidge grow box. This is a full size fridge that will be gutted. I will have a 4" computer fan in the top for exhaust and a 4" passive intake. I will also have 2 - 3" fans inside one on the lights the other on the plants. Should i go for a 150 w or 250 w they are both remote ballasts.

Any advise would be appreciated

as long as you can control the heat, the more light the better. think cooltube