That's what I currently run in a tent , 5x5 with a 1,000w hps and a blackstar chrome. 270. I owe a few LEDs a couple from blackstar, a couple from bysen ( direct from china and very legit , good warranty) , and the Cali works solar storm 400w (my least impressed led of the lot to be truthful) a 600w hps with the led would be PERFECT IMHO for your setup... At one point when I had the 4x4 I had four LEDs in there... Also had good results but I just think besides the heat the hid lightening mixed with led is best IMHO.... I think the more of spectrum of light you can replicate the better off you are... I ran a few grows with mixed flowering spectrum and some mh and the mh really kicked up the trich production... (As the uv bulbs from the Cali works light do as well, but you can just by a few t5 fixtures and run a few uv last couple of weeks of flowering... ) I've done a side by side one tent with the uv and the other under the hps/led... Obviously bigger yield under the 1,000w but def much frostier though more airy nugs under the Cali light.... Good luck in whatever you decide.... Even consider two 250w hid's so you can have the luxury of hanging at different heights to maximize the light that gets to the canopy if you have plants of different heights...
Best of luck, and looking forward to watching the rest of this unfold...