HELP! best usage of my space?

I'm planning a growbox (limited space):
21.5"X48" 64" tall
400w hps
soil grow
first grow

I'm positive I can do two very nice plants in my space, but would it be worth it to try and squeeze three or four in there.

Strain recomendations for my situation would be appreciated too.

bump.................

i'm guessing a closet? i would look into LST or SrOG you would get the best bang for your buck.

indica strain. Don't be greedy...grow 2 more space more light for those 2 plants better buds