green2012,
I work in the entertainment industry, designing and building special effects and theatrical automation. I also rig and fly performers; think Peter Pan, and the like. I see and use rigging on an almost daily basis; please PLEASE PLEASE involve a structural engineer and a rigging expert in this endeavor. 200# is more than enough to severely injure or even kill someone.
Where are you located geographically? Is seismic loading a concern?
Please understand I mean no disrespect when I say this: well-meaning electrical contractors, while being exceptional at their jobs as electrical professionals, are not riggers. I have worked in more than a few entertainment venues where the EC got the bid to do the rigging, and the results were pretty uniformly a mess.
Rigging and the suspension of heavy things over people's heads is a specialty and art form unto itself. If you can't define and use terms like "ultimate breaking strength," "minimum breaking strength," "design factor," "dynamic load," and the actual, legal meaning of "rated hardware," it behooves you to enlist the help of a specialist. It's often more involved than simply bridging some rafters with Unistrut.
Where are you located geographically? I may be able to recommend a company in your general area that might be able to help. Failing that, try a search for "theatrical rigging companies" on Google.
I've seen the aftermath of rigging failures; messy, expensive, and sometimes deadly. You owe it to yourself and your client to do this correctly. Knowing that something won't fail is much different than knowing it hasn't failed yet. Gravity is a demanding mistress, and will not be ignored.
-SceneryDriver