My friend and former boss Barry Sulkin worked in the parts department of Honda Del Rey, on Sepulveda Blvd. in Marina Del Rey. It was one of many small Mom & Pop Honda dealers in the Los Angeles area at the time.
He said that occasionally, the test riders from American Honda in Gardena, about 15 miles away, would come into the dealer for whatever reason, and he remembers seeing a CB750 with a front drum brake. I had never seen any pics of or reference to one, so I forwarded it to him.
He had the opportunity to buys a factory dry sump tube frame scrambler, passed on it. The opportunity to buy a CR72 for $500 from a customer came and went because he couldn't scrape it up, even after a year's time.