my 400w scrog plan - advice pls.

A friend has been thinking about a scrog at his place. He lives in a small shared house with a one room set-up kind of thing.
he has a small cabinet. He has a 400w hps bulb. I told him id get the relivent info from here cos he has no web access.

the distance between the soil and screen wuill be 10 inches, the distance between the screen and light will be variable between 10 and 14 inches. If the light is fitted with a home made cool tube will this setup be kosher? what other considerations should be taken onboard?.
also what kind of yield would be expected from this rig?

cheers xx

Just make sure you have an air-cooled hood. Also you can use air in and exhaust out as well. A small fan moving air around the tops of your plants are a must keep it on 24/7. Monitor the temperature under the light at the top of the canopy and you will do fine.

am i right in thinking a good time to train the stems would be when they penetrate the screen about 4 inches? and as for the yield i suppose its so variable. But what could be a good goal to aim for qith a 4 plant scrog first grow?