All three bikes use virtually exactly the same switchgear housing...& as has been said, the only differance may well be the wiring. On my early CB550F1 the wiring went though the bars via an elongated hole to the box by the front left of the fuel tank. But on my CB550K3 the wiring was external of the handle bars & went into the back of the enlarged headlight shell.
So if you did choose to buy a good condition unit that was meant for a CB400/4, it would fit...anything can be made to work. I fitted a left hand switchgear from a CB125TD Superdream onto my modified CB750F2, because I could use the indicator switch to actuate the headlight, & the headlight pass switch as the electric starter button. It kept all of the switching on the one handle bar/clip-on, freeing up the right side for the quick action throttle from a Honda XL250SA.