That is a cool engine to use for a project like this. You already have the kickstart and transmission right off the bat. You can't beat that. It will be an instant motorcycle though, not a bad thing. I would attempt to find a motorcycle wreck at a dismantler or wrecking yard and find a motorcycle frame with a registration so you can transfer the VIN plate to your new bike. By the book the law says you need one foot length of original frame with the VIN stamp on it transferred to the new frame to call it a legal "upgrade", but I don't think anyone will mess with you if you use less than 12". By doing all of this it would prevent you from needing to go through a new build process that is quite extensive. It would allow you to register the bike without needing to get CARB certification for the Lifan engine, which would probably be impossible in CA too. Don't forget about a mirror, horn, and lights. My Moped registration exempted me from a working brake lamp or turn signals. I don't know if you would need to have these or just be allowed to use hand signals for that. Being on a "moped" as I am, I still need to use hand turn signals and hand brake signals. People with authentic antique motorcycles and cars don't have the brake lamps or turn indicators as well and need to use hand signals, so maybe having a replica would "exempt" you on that. But anyway, very nice build and I'll be watching your progress.