Yes please do, and if your planning on running more that the 830W CDM I HIGHLY recommend you get a circular light mover (light rotator like the Solar Revolution), mount the vertical OG hood with the 830W CDM bulb in the middle and then put two other hoods with 600W HPS on either side (so all three hoods in a strait line mounted on the light rotator, so 600W HPS-830W CDM-600W HPS), this setup will grow plants like you've never seen before, you would be amazed with what it could produce, however it won't be cheap but things that are worth it rarely are, lol.
I'm not contractor or anything and maybe you know something I don't but, really? I though as long as you find a beam/stud/joist you should be fine, a 400W mag ballast doesn't weigh that much (50lbs or so??), I mean a friend of mine has a sex swing that's secured into a beam in the sealing and they claim to "Go At It" all the time with no problems, the beams are usually 2x4's which should easily be able to hold a 400W ballast, just get an eye bolt from the hardware store and it should hold it just fine, unless you have a really old house with rotted beams that is.