If you have a 600 watt HPS..... you would be better off selling your mars LED and buying a cheap home depot bathroom exhaust and some dryer vent tubing... that and a small 15 dollar fan at the other end and you have all the ventilation you need. You WILL be able to get a 1/2 or more with that light. You WILL be in shock and awe at how well HPS flowers compared to everything else. I had a 2x4 storage cab grow with only 150watt HPS and a 4 foot T12 shoplight.. i got 8oz of four small plants using scrog. (sound like a fish story but it happened and worked for three grows till i stopped for a while) I have not seen anything anywhere that proves to me that LEDs are better than HID lights for penetration and dense buds. In my experience, CFLs suck. I currently have five seedlings under 55watt CFL and a small T5 28watt strip..... I am stunned that they pull away from the CFL and are stretching toward the little T5. the CFL is too hot and my plants and I decided we dont like it at all. If you are using flouros, T5 (at 99 lumens per watt) is the absolute best bang for your buck... however, they are relatively expensive (sitll cheaper than LEDs).... T8s work and get about 90lums per watt but you can not beat T5s and HPS (what i'm using now for flowering). You can pick up a 4 light T8 shop light at Walmart for 12 bucks.
There are a lot of options but trust some of the people here to help you out... you CAN grow with what you have, you'll just have airy buds that dont fill in much past the top few inches. Not a disaster, and still awesome because you did it yourself, but you can do better with that space without spending ridiculous amounts of money. Good luck!