Dirk,
I agree with Chasmtz, in that your ambition and work ethic is clearly top notch. I'd love to have you working in my grow op. You're going for what may be impossible with total zeal. It's better to have tried and fail, than to have never tried at all. I truly hope you can pull this off and prove us all wrong. I have a feeling you already purchased the lights. Yes? Did you, by chance, get dimable ballasts? Please say yes. That mey be your saving grace. Just keep in mind that you need 24" between the bulb of a 1000 and the plant tops.
1000 watt bulbs are great. I run 18 of them right now. But, I have 10' ceilings. If it's in the realm of possibility, try to get some lower wattage lights. I still would say T-5's would be ideal with your space. You could always sell the 1000's to ease the $$$ pain of buying a whole new suite of lights. I just would hate to see you move forward with something that just can't work. Please...what is the distance from the joists to the top of the pipes? You'll be fine tucking air cooled reflectors between the joists...as long as you have good airflow. DO NOT daisy chain all of your lights. I never daisy chain more than 3 lights with a 740cfm inline fan. Even with that, the last light is pretty warm. If you can grow the plants to a finished height of, say, 14" and still have 24" between the plant tops and the light....GO FOR IT! You'll have to space the plants pretty tight to get a good yield, but that's ok. I'm thinking around 4 plants per sq ft. If you can do that, and keep the atmosphere right, you will blow us all away with your yield. I'm talking a sea of donkey dicks. I've planted several canopies wit 16" plants, 4 plants per sq ft, and had yields of 2 oz/sq ft. All you need is 1/2 ounce per plant.
Well, my man. I'll let you get to it. Alot of us are pulling for you. If you're ever in So Cal and need a grow-room job, send me a PM. I'll hire you tomorrow. I know you're not a cop. No cop would have the balls to even talk about what you're trying to pull off. Go get em, turbo.