i would say that if you are going to build your own canopy, to hang it from pulley's that way whenever you wat to get into the tank you can pull down on th epulley, and latch a hook onto some chain, and the canopy will be suspended up much higher. i would also say use the 250w mh's i personally liek the AB bulbs that are 10K because they actually burn at about 13K. make sure to wire in the canopy a couple fans, and ditch the glass tops, this will increase evaporation, but will also help to keep the tank cooler. im a big fan of the light on a pulley thing. i will try to draw a pic of what i am talking about and will take pics of my canopy over thanksgivign to let you see what i have done!
good luck
jon