Are we still don't know much about you or what tools and skills you have but at least we know where you are now. I don't think you will find those bits in a small shaft size to fit your router. What you might be able to find is a 30* bevel bit though. If the edges of each board were beveled at that angle then that should equal 360* total and you would have a full circle. In order to get a taper you would need to taper the boards first and without knowing more about you I can't suggest how you should do that.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.