new grow closet, need advice

[loolagigi]

well here we go. i have a blank closet that has never been grown in before. in the pics it shows a cabinet i used to grow in. i could only fit 2 dwc buckets in the cabinet and used a 400 hps to flower. i wound up with about 1/4 lb or so. well its time to upgrade! tax moneys comming in and i would like to grow at least 1 lb of medicine. the closets dimensions are..5x4.5x8' tall. in my worls that 180 cubic feet right? well i still have my 400 watt hps which is a magnetic ballast. the bulb is a hortilux and its in a diy cooltube. i also have a 465 cfm squrel cage fan that i used to cool the cooltube. well that just about all my "tools". not sure if i should keep my cab to veg in, or get a smaller one.? also if i do keep it, i thought about placing 2 400 watt cooltubes verticle, one above the other, and having the plants in a L shape around the cabinet. will i get a lb out of 2-400 watters in the right conditions?
should i just get another 400 hps and make another cool tube, then cool both of them using the 465 cfm? or should i go another route. also i used to run my cooltube horizontal...with a homemade reflector. i read somewhere that running verticle lights and no reflector will make my light more efficient. any feedback would be appreciated. Loola