Hi tim,
You asked about convex mirrors in another thread; my posting about being smacked by a car while I was sitting still at a red light. I have not posted follow ups to that thread as of yet.
The mirrors on my CB750 K4, which were stock, were flat mirrors. On the backside of the mirrors there was a impression in the metal with the Honda Motor Company logo.
I do not recall ever seeing convex mirrors, on these bikes, made by Honda. Not to rule it out as an impossible thing to obtain; Honda has made so many different models over so many years...... they could be out there somewhere. I remember rectangular wide view mirrors on some early (1960?) Honda bikes.....
~ ~ ~ jaknight ~ ~ ~