I would do 4x50w multi chip LEDs whatever color you like maybe warm white or cool white. Cree has some great lamps like this, I think they are called xpg's for about $30 each. Get you 2 heatsinks around 6-8" x 18-20" in size. And run the 50w LEDs at 30w, so a led
driver at 36v and 1000mA for each led
. You could add a dimmer if you like, you may have to dim each one individually, or instead get a single powersupply for all four LEDs. It would be 36v 4000mA .
This is just one route or you could do it with teo fixtures of 15 x 3w LEDs with similar heatsinks and power supplies.