Your biggest problem will be getting light to the bottom buds, you will need atleast a 600w if not 1000w HPS above and then hang some 150w HPS lamps vertical around the sides of it to get light to the bottom. You could accomplish the same thing with less light if you take one plant do a scrog with it, let it veg for a long time and get it spread out over a 4' by 4' area.