The grow box size you described is identical to the one I used for my first grow. For lighting I started out with a 24" x2 flourescents w/F20/T12's that I got from Lowe's. I kept the light about one inch from the top of the plants using adjustable chains mounted on the top of the cab. I used a small fan and had it all connected to a timer. I sealed it so that during the dark part of the light cycle, absolutly no light penetrated the cab.
My first grow was some haze seeds and I found that after I started the flowering cycle they were getting too tall so I had to do some Light Stress Training.
The harvest was not real abundant...but I learned alot on that first grow.


I am now in the middle of my second grow using the same cabinet only now Im using the same 24" lights with an addtional 48"x2 standing streight up on its side plus 4 100watt cfl singles.
And since the cab is somewhat on the short side I decided to go with some Lowrider autoflowering AK47's this time around..So far my plants are 1.5 months old and doing good, & flowering like crazy considering that my light source is kinda meager compared to other growers here on this site.
Good luck to you on your first grow!:thumbsup: