Just reading an article as below re CB750 production demands. Used a Suzuki factory!!
"It became clear that the production of the original sand-molded crankcases would never meet the rate requirements of mass production, so the factory switched over to producing crankcases of a metal, die-cast construction. The bikes were such a hit with the riding public that the production of engines and chassis was moved to a Suzuki factory in mid-1971."
Full article FYI.
https://www.autoevolution.com/news/the-honda-cb750-changed-the-way-motorcycles-were-made-raced-and-sold-171785.html