Not super easy to answer adequately. The OEM switch does quite a few things. Plus, how will you mount a replacement non-original keyswitch? The mounting is a bit bizarre, maybe some other Hondas used this switch body but I don't know which. Honda either got the wiring diagram wrong or used wire colors in a very odd way, ie the horn has a black wire to both its power and its grounding button... the black wire also turns into black/red (?).
Anyway... the factory wiring diagram does not include switch contact tables as found on the SOHC4 diagrams, so we have to either guess or measure what connects to what in the 3 positions. I did not measure one, these are guesses.
OFF (CCW stop, key comes out): presumably does not connect any terminals to any others.
ON (middle stop, key retained): Gets complicated but probably connects the battery "+" red wire to the black wire - general key-on power to ignition coils and horn, stop light, etc. Also connects battery to the lighting switch, and finally the tail light (and "parking" lamp) is connected to the lighting switch (see PARK position).
Then there's the rectifier... not sure why it even connects to the CH terminal. A puzzler. It already connects directly to the battery + according to the diagram. If anyone knows, share that secret.
PARK (CW stop, key comes out): Just powers the tail light and "parking" lamp (a small bulb in some headlights). That's so you can park your bike with marker lights on to deter collisions with it, then go to a movie and have a dead battery when you get back. The red BAT wire is connected to the white tail light wire which is also disconnected from the "lighting on" green wire.
To get very basic keyswitch replacement, you need a two terminal on/off switch with two positions, OFF and ON. The red wire to one terminal and all the other wires except white/red, green and white go to the other terminal: you need to splice green directly to white to have the tail light come on with headlight on, wrap some tape around white/red (this connects unfused to battery "+" and if it touches metal... very bad stuff happens).
Everything works in ON, nothing is powered in OFF. That eliminates the PARK function which nobody I know has ever used except to see what it does. You could connect a SPST toggle switch out of sight this way, and keep the keyswitch just for decoration - even continue to use the key as if it did something.
If you use an automotive switch you could connect it to use the start position, but ignore the accessory terminal (and position)... what would you want powered there?
Maybe another 60s Honda bike like a CB450 has a switch with the same mounting and wiring configuration, I don't know. Good luck!
