You are a bit more sophisticated than some of us, lol....
I just go by the 50 watts of HID per square foot, and use the best bulbs I can find to squeeze out a couple more lumens.
I'm happily running 1400w HPS in a 5x6 space.

Your issue is going to be DISTRIBUTION, since you want big ass honkin' bitches. If I wanted to grow that style, I would switch to 4 vertical-burning HPS600s in parabolic reflectors. ATM my plants are under a single 1000 and a 400 (when they first enter the flower room), and they have to be bent over short to take advantage of the light. With multiple points of light, you get the luxury of side lighting to your big bushes.
Just some thoughts. I think BlueBear- who was growing BIG plants- was running parabolics.

__________________
"Careful what you carry- 'cause the Man is wise- you are still an outlaw in their eyes" -Steely Dan
"Multiple pieces of anecdotal evidence do not equal scientific fact." -Rhizome
"If the Queen Bee ain't happy... the hive isn't happy!"-Dutch Pimp
http://boards.cannabis.com/basic-gro...e-harvest.html<-It's a grow guide! Enjoy!
http://boards.cannabis.com/plant-pro...hy-how-do.html <- all the boring stuff about soil chemistry you never wanted to know
http://boards.cannabis.com/grow-log/...ml#post1837597 <-how to make canna caramels
http://boards.cannabis.com/grow-log/...ml#post1820481 <-illustrated cloning guide permalink
Contacting Her Dankness: stinkyattic at hushm4il-please use the same discretion you do on the boards, thanks.
I don't claim to know the first thing about growing anything; hell, I can't make a Chia pet sprout.