A 600 watt HPS/MH would perform well with those specs. I don't know about not requiring a ballast :jointsmile: but a digital ballast works well and keeps the temps down a little bit more if you have to keep it inside the tent. I have about the same measurments you have and do pretty good with my 2 400 watt hps cooled with a 6 inch. 600's would've been peerrffecctt for me.

If you can shell out the extra money and say the hell with it and get a 1000 but you'd need a nice fan to cool that down. Its less hassle with just a big light lighting everything you never have to move it or adjust it.