Your cabinet size is pretty much the same as mine and I run a 400w cooltube. If you get yourself one of the newer "smart" lights that can run both MH and HPS bulbs you can MH for veg and HPS for flower and a single 400w light should be plenty. Careful with the Mylar when installing, from what I have read sometimes hard to put up without tearing or getting wrinkles and creating hotspots. As an alternative Koolseal white metal roofing paint has like 90% reflectivity, no hotspots and doesnt tear :thumbsup: and runs about $20 a gallon. I did all walls inside of mine with 5 coats and still have 3/4 of a gallon left.