Your're gonna need more height. MJ grows up. A nice plant is 3-5 feet tall. Heat is your main problem in a space that small. You will need A/C or wait until winter using fans. A 600 will have to be at least 15 inches from the top of the plants, maybe more. 1000 maybe 20 inches or more. This is the ZONE you have to keep at 75-85 degrees.

I grew 13 female plants under a 400HPS in the same size closet, except for the height thingy. But I rotated 6/7 every 12 hours. They were 5 1/2 feet tall at harvest....enjoy....imp: