You're on the right track. At least I do a similar approach. But, I don't use an o-ring to keep the brass on. I glue it on after I insert the reed. But, try your approach. It may be better.
You'll find that THO is a great source for learning how other folks make calls. But, part of the fun is trying new things, making mistakes, and learning from them.
Good luck. And be sure to post pics of how it comes out.