That's alot of light. It will definitely work, but if you get those Lumenarc reflectors I linked to previously, you can get away with 2 250w MH and 2 T5HO for supplemental lighting. Even tho T5's are thin, using them with
individual reflectors at 2" wide each, they will take up some space. 6 bulbs x 2" each = 12" for the T5 setup....leaving you a 6" opening for the MH's if you mount the T5's 3 in front and 3 in back.