Re: We're not sure what to call him
I think you need to be clear about what you are trying to accomplish.
Is this about a title? Or about describing what his responsibilities are?
One of things that I've found very annoying over the years in business is when a company will bestow a title and then try to figure out what that person actually is supposed to do. A title, in my mind, should be nothing more nor less than a short description of responsibility.
Dojocho - head of the dojo. The guy in charge. Chief instructor.
Kyucho - (as was suggested) ought to be similar to dojocho only applying only to mudansha.
It seems like it's really easy to overthink this. What's he do? That should be sufficient to determine his "title".