Steve, I have friends - the best of the best- in the CBX world. I don't own a CBX Myself but these guys restore them and build the engines: Bill Brint of Tims CBX in Cornelia, GA and Roger Twito (an execellent engine builder) in Bethpage, TN. They built my GPz 750 Turbo and are both great guys, I can put you in touch with either of your interested.
Www.timscbx.com, I don't think Bill keeps the webpage up though.