Find out what the thread pitch is and them go shopping at McMaster Carr. If they don't have it, Guitar has a good idea but I don't think you want to know what a quality tap and drill that size will cost. I'm pretty sure a couple of hours at a good machine shop would be cheaper and I think you could bore and cut new threads on a lathe in about an hour. After you set up the first one, you could have some spares made with not much extra time involved.

Kevin