Danlboy,
I just hate to keep harpin on this, but I guess my assumption's were correct? about the picture on the web site....I take it that, this is the one you purchased?

I really just can't see a 600hps or even a 400hps burning away with the doors closed.
I went back and let the whole page load, so I could have a better view of whats going on. However I didn't get into reading the entire page so...

First impression's weren't good to me on the first go around.
Second impression after viewing the picture's is... run like hell:dance:
Not sure if thats an intake toward the bottom, but if it is then thats a bad idea for a light-trap. I could go on about this box.....but hell...If I can put the joint down long enough I'm sure I could re-design my box abit better too.
A couple points I'd like to make..
Again there's no harm towards you, or any other person that may purchase these design's. I like ya already just for doin the right thing by growin your own. And I can understand the attraction towards item's like these. They promise this and that, or maybe I should say they advertise while pulling on your strings...and afew other things wording things just right.
You said you have some time in indoors. However you also said this was back in the 70's w/floro's. Not to mention you called the buds desent. So with that in mind i'd say you have limited time in with indoors and hps bulbs.
These puppies can burn hot! A 600watter is gonna throw some heat out.
I run a 250hps, with a 350-450(..i forget) inline fan on a dimmer switch. I'm not comfortable running anythign more then a 250. The reason is simple...if my fan goes on me, or my timer(s) fail, I'll still have enough time to react. I'm also able to keep the plants right on the glass if I use my dimmer switch.

My fan is 15min. on/off I really don't have to turn it on till about every 30 min. or so, but I want to be safe, and allow fresh air in.
if that fan of yours goes south on ya then your reaction time better be asap.
I've witnessed an entire 120 delightfully sweet plants go down the drain just because of this! from then on it's always on my mind when looking at or designing a new cabinet.
What ever fan they have provided you with is gonna have to be something with major kick ass power, and reliabilty.
If you give yourself some time and confidence i'm sure you can build something that will blow the doors off of this thing.
IMO your just about there really. Better off then you think maybe...
I'd use this box for a clone chamber...just throw in afew cfl's and your gold!
Take the 600w and fan, and design a space/cabinet/closet ect. just for that stuff. A 600w and 30" is not considerd an optimal garden IMO. You could do soooo much better for yourself, and be able to harvest a pound of grass given the right diamentions/genetics. King of the mountain as they say:thumbsup: