i say tht u buy the pack of the 23 watts an the 42 watt at the same time put them all in there cuz with cfls the more the better cant have too many it will work good an add 1 or 2 more single 23 watt bulbs in there as well u should be set after tht
u need light paint ur box flat white or use mylar to reflect light back to the plant an exhuast fan postioned at the upper part of ur box (hot air rises ) an a intake at the bottom just use computer fans . timers