400w or 600w for a C13 type cab?

Question, I am constructing a new cab similar to the C13, 48 x 20 x 72, and am wanting to put a 600w with a digital ballast in it. Would it be better to put a 400w with CFL side lighting and either way what cfm fan should I use? I want more lumins PSF, but don't want to over kill the cab. I am thinking about going with a 300 plus cfm Squirrel cage fan with a can filter vented under my house with the fan under the house as well. Oh yeh, I will be going the air cooled hood rout and just venting all the air from the cab from the whole cab through the air cooled hood because the ambient temps are in the low 60's to the upper 50's with 2 8' dark room louvers for passive intake. Also, I am doing SOG style and the hood for both the 400w and the 600w is only 20- long so I am a bit consern over the light coverage. I read a old thread that touched on the same question, but I am looking for any other and also newer opinions on the question.
Adieu

You'll have plenty of light PSF with a 400W light. I would suggest you make a cabinet deeper than 20", though...allows for more room for your lighting hardware and can put in an additional plant, perhaps, while keeping you watts PSF at an acceptable level...I suggest 2-3 feet deep instead of 20".

Good luck!