Morty Vicar
Banned
^^^ I think people are mixing up ethnic Jews and religious Jews above. It's entirely possible for them to be prejudiced against ethnic Jews but still follow the religion of Judaism.
As far as Orthodox Judaism is concerned the two are one and the same, people are either Jewish or Goyim, a convert is as Jewish as someone born to a Jewish mother. Judaism makes no distinction between Jews who have converted and ethnic jews, thats a label largely applied by outsiders who label people of Hebrew semitic origin as jews, regardless of their religious beliefs (or lack thereof). Also in the case of the Black Hebrew Israelites their religion is not Judaism in the traditional sense, but rather a syncretic religion.
Anyway, I think you'd probably need to raise their profile significantly for Muhammad Ali (well, Cassius Clay at the time) to notice them and want to join. The Nation of Islam was very high-profile at the time of Ali's conversion -- after all, they had Malcolm X.
Although Ali was motivated greatly by the civil rights struggle, he became a devoted follower of Sunni Islam later, suggesting he also had purely spiritual/ religious reasons, which mean he could essentially have adopted any religion (especially considering some of the, lets say, slightly more radical claims of the NoI). If he met Martin Luther King he may well have reaffirmed his Baptist faith. You're right about the Black hebrew Israelites though, they were basically a nonentity at the time, only just beginning in fact, sorry for my lazy research there. There were earlier similar Black Pseudo-Jewish movements, but none which seems likely to cross paths with Clay. Just an afterthought, it would be cool if he had become a Rasta!