Is this enough space and ventilation for a 400w hps?

I want to build a flowering box for 8 3ft(at harvest) plants that is 3ft wide 2ft deep and 6ft tall Is this enough space??

I will use the bottom foot for my ebbnflow reservoir, the middle 3 feet for plant growth and the top 2 feet for lighting.

makeing it 36 cubic feet of space all together (30 feet if you don't count the reservoir area) and 18 cubic feet for the plant under the light

I want to ventilate using a squirrel cage fan that is pulling air from a hole in the light reflector,put an intake hole near the plant base, and of course use mylar over all the walls.

If i can keep the outer room the box is stored in at below 70 degrees fahrenheit do you think it will be a good plant environment.

ANY INPUT WILL HELP AS I HAVE NOT GROWN BEFORE AND WANT THE BOXTO MEET MY NEEDS AS BEST I CAN MAKE IT.

I'm not sure about humidity levels in the room yet but will get a humidifier or dehumidifier based on what i find...also I hear that ideal is between 50-80% what do you think is best and at what temp??

alright man so basically you want to fit 8 plants in there. you have a 3x2 base. well man i would say that if oyu fit 8 plants in there they will be a little cramped man.they say a sqr foot per plant.so a 3x2 would be 6 plants. you can make it a 3x3 and get 9 plants in there but thats cramped to man. make it 4x2 and you should be fine also.do 2 rows of 4. also what light are you using and does hte 2 feet include space underneath the light also? if you got a hid light than you will need a couple inches between the light if it is air colled if it isnt it may take a foot depending on the light size.
also if htis is your first grow wish you good luck wi the the ebbnflow. that sometimes messes up begginer growers. but man you got a good setup but oyu might be asking for to many plants....but if you really want 8 plants then you could look into sog. sea of green. roughly its hwere you prune the lower branches so it focuses on a main cola but it hels with width growth and also height if that becomes a problem