The previous owner cut the stock plug off, so I wasn't feeling too bad about relocating my switch. You can see mine mounted to a bracket I waterjet just below my side cover. It's out of the way, and not noticeable while riding but still easy to reach.
I used the switch from Lossa, pretty sure some other vendors sell the same one.
Also on a '78 CB550, but far from a factory ignition mounting solution. I like FunJimmy's stock-adapted ignition!