If I had a theory, it might be simpler to manufacture. A couple less pieces inside the speedometer and tach, and a (mostly) one-piece casting for the handlebar dash. It might have been the style of the time too, trying to distance the bike from "old fashioned" design cues. But this is pure speculation on my part.
As for my original question- yeah, that's perfect. I had a feeling it had to be something close to this, but this answers a lot of the detail questions.
You see, I've got a vaguely 1970-ish CB750 I've essentially built from parts. It's not any one year, one style, etc. The frame is a '74 or '75, the engine is a '72 top end with a '71 bottom end, it's got an early back end and a late front end, HM300 pipes- it's a mess. Well, since "period correct" means nothing to this thing, I'm debating on just dating it to a year I like best instead. I love a lot of the style details of the K0 bikes, and am pondering the possibility of back-dating it.
I've got a whole list of stuff to do, and gauges were one of them. I might be able to modify mine without too much trouble, but as they say the devil is in the details. So we'll see.
Another question- I know the '71 gauges onward are assembled together with a chrome crimped ring. What about the early '69/'70 ones, with the plastic housing? How are those sealed?