Pj, I've used stainless valves on cast guides for years in automotive application. The KPMI valves are microscopically coated anyway, should not need bronze guides according to their tech qa https://www.kpmi.us/tech-support---faq.html
I did in fact call them and they assured me the factory guides in cb350s and cb360s have been used successfully.
I did in fact call them and they assured me the factory guides in cb350s and cb360s have been used successfully.