The "only" way that I forsee a 400 possibly working in that tight of space, is by sealing the hood off and directly venting it, or a "cool" tube.
A SCROG under cfls/flouro's is probably your best option in that space. It simply isn't tall enough to accomodate HID lighting..."IMHO"
3 feet, less 1 foot for pots, less 1 foot for the HID, and the heat generated from a HID 'requires' space between the lamp and the plants. You're outta verticle space before you get started.