My uncle raced the BSA until 1981. He and the bike have been retired from racing since then. He still has the bike.
Ancientdad. I think this bike may have raced a few of those men. It's Champion framed. Serial # 25. Also the BMWs and another 8 or 10 Indians as well as several BSAs and a Vincent Black Shadow in the collection. To many others to remember.
You should ask him about it, I'd love to hear more of his racing life. I'm sure he has many stories to tell.