Man, that's going to be expensive upfront to buy good lights.. Then technology will leapfrog by this time next year. I'd stick with HID although LED is so tempting. The CMH lamps have become pretty affordable and are pretty efficient. There is a 630w CMH now.
Rectangular space... find a brand you like. Check out what they recommend. It's not alwYs quite the same. Plus I would go with several smaller lights at that size as well.
Plus you got the blurples, the cobs and all sorts of different led.