I talked with Leonard about the group. I'm interested in the stories on any Ohio artists so I was very glad to get the first person account on a group that was not well documented. Leonard had a lot of cool stories to share.
All the members were from Toledo, they started as high school aged students, they were 5 as the Proto Jays (including the 3 mentioned above), and that, according to Leonard, was the group that recorded the 45. The Rivieras came after, but not that long after. They performed a lot in Detroit but also played Toledo and northern Ohio, including the Ken Hawkins World Of Soul TV show from Cleveland (there is no surviving footage from this show).
In terms of dates, the Proto Jays 45 seems to date from late 1967 or early 1968, a couple months before Diamond Jim's store on Dexter was bombed (May 1968). Diamond Jim was killed in May 1971, I assume this is well known to Detroit music historians.
My goal was to post the story on my website, with pics, once I've talked more, so I hope to make that happen. I wasn't really planning to post anything until I had all the info but at least I could share something, for sure to confirm the group was from Toledo.