First off, I am no expert on anything. I have however chased a ring on black locust with no drawknife. If that was my stave, I wouldn't want to ruin it. My thought: if you are planning to chase second ring, practice chasing the first. I tried it with a big hunting knife that you can hold in two hands sort of like a drawknife...
I also found a drawknife made from an old scythe with an extra handle attached - useful tool.
By the way - what a great problem to have: a beautiful piece of osage, wondering how to handle it!
G