All of the above is sound advice. I would add that if you don't have experience in this type of heavy rigging, find someone who does. There are many subtle points which can become critical issues if executed incorrectly. There are usually several things happening at several places at the same time, all of which must be monitored closely. The safety risks are too great to be tackled by a novice. It's hard to say without seeing the project, but it may be a relatively safe job, or a disaster waiting to happen. I favor the conservative approach and at least getting the input of a professional who has seen the barn. Good luck and PLEASE BE CAREFUL!!!!!
