Akimbo,
I started diving in 1959, with a double hose Healthways SCUBA regulator. My second regulator was a single hose Healthways Scuba Star regulator, which had a restrictor orifice and I think I used it with a K-valve (no SPG). We were given a demonstration of the strength of the LP hose when a dive shop cut one half in two, and asked people to try to break it completely (we couldn't). He then showed us a photo of one of the HP SPG hoses between to pickup trucks, and they could not rip a half-cut hose in two. It was a pretty good demonstration of the strength of these hoses. Most of our dive club, the Salem Junior Aqua Club, used single hose regulators with and without an SPG (see the photo of Pierre with his dive gear below, using a SPG).
My third regulator was an AFM Voit 40 Fathom single hose regulator (Voit's version of the first USD Calypso regulator), which I used from about 1966 to the mid-1978. As a USAF pararescueman, we went through the U.S. Navy School for Underwater Swimmers, and we used the DA Aquamaster exclusively. After graduation as a PJ, we used single hose regulators with twin tanks (either twin 42s or twin 72s) through the 1970s.
I became a NAUI Instructor (NAUI #2710) in 1972, and we were not required to have an SPG at that time, or an octopus. My first use of an octopus was on the Warm Mineral Springs Underwater Archeological Project, and that was at the insistence of Larry Murphy, in February of 1975. By that time I had converted to an interesting type of BC that was built into the back of my wetsuit by Bill Herter of Deep Sea Bill's in Newport, Oregon.
In 1974 I published two articles in the IQ6, or Sixth International Conference on Underwater Education, sponsored by NAUI. One was titled "The Life Vest," and the other was titled "Comments on Buoyancy Control and Emergency Procedures." I used my brother, Ken as a subject, and he wore a life vest, single AL72 (the floater) and my MR-12 single hose regulator (no SPG, no Octopus). Around this time, Jim Mitchell published several drawings for NAUI showing both buddy breathing and the use of the octopus. Another drawing below comes, I think, from The New Science of Skin and Scuba Diving from the 1960s, and shows buddy breathing with the single hose regulator.
Limons Osis, an Oregon Department of Fish and Wildlife Biologist, is using a Healthways Scubair with a SPG in 1975. So at that time the SPG was becoming known, but not necessarily used a lot.
SeaRat