Changes that I would implement for the monk if a player at my table selected the class:
- If you are unarmed, your martial arts die increases by one step.
- Flurry of Blows, Patient Defense, and Step of the Wind do not require ki points, just your bonus action.
- Stunning Strike is replaced by something else. I'm not sure what. Probably levels of exhaustion.
You could balance the monk around that, making the basic functionality ki less and then making ki points a per day resource maybe. And stunning strike could be a prof bonus per day thing.