Did you check your local dealer? You'd be suprized what they can still get(new!). If not check for a used bike of the same year for parts, or go to your local motorcycle salvage yard. If you really want to set it permently, I guess epoxy could do it. The position depends on the type of riding you do. Closed means more low end power and less top end power. Open means less(much less) low end power, but good top end power. So if you like to take it easy and rev it low, go for the closed position or, if you like to have it wide open all the time, go for the open position. But keep in mind that setting it with epoxy is a permanent fix and can not be reversed. I'd try and fix it with new or used parts(even machined parts) befor going the epoxy way.
SS