Proper ventilation in tent?

Hey guys, setting up a grow room for my friend. He has a GL120L growroom that is 3'11"x7'11"x6'7". I plan on running two 600watt metal halide bulbs in air cooled reflectors. My question is, would a 6" fan and ducting be sufficient to keep the tent cool? Also, what would be a good amount of plants to fit in this tent? Growing in soil. Any help is appreciated!

It depends on what kind of light you have and how hot it gets in there. In the winter time your probably ok but in the summer you'll probably need to add a fan or two (you should have them anyway for air circulation).