Chisango might've been popular but you cannot have a simpler, more common name than John Fighter (9-10). https://boxrec.com/de/box-pro/131251
Okay I went to South Africa & Zimbabwe to do on-site research. Talking to many old trainers, fight fans and retired fighters and listening to hundreds of anecdotes, once story kept popping up: the hugely wasted potential of the incredibly promising young talent, Johan de Beer (9-6-2, 3KO). https://boxrec.com/en/box-pro/96132#google_vignette Apparently, he had a drinking problem.
His record on boxrec is incomplete. I am certain he continued his career after the Flash Chisango fight. He relocated to South America and had a cult following in Argentina or Paraguay, if I remember rightly.