This could be a solution to some of your rust issues . . .
Years ago I was looking for a Harley Sportster (Buell actually) motor for a custom build. Never really found the wrecked bike or basket case I was hoping for, but then I found this:
A complete running and registered bike. What is topical here is that the guy who built it pretty much dry fit everything, then torqued it all down and sprayed everything with bbq paint. I mean everything. Nuts, bolts, capscrews, wheels (some overspray on the tires), spokes, hubs, brake line fittings, exhaust . . . everything. Take the air filter off and half the carb was black, the other half polished aluminum (S&S Super E).
Crazy Australian guy, I remember he intentionally scuffed part of the frame when I was looking at it then pulled out a can and sprayed over the scuff. "There you go mate, no worries!"
I'm just suggesting a relatively direct and foolproof direction for your bike. It might be near worthless afterwards, but what the hell.
So what happened to the bike pictured above? Bought it for a song, gutted the frame and built this:
It's not Honda, I know, just thought I'd share.