Norton had been in poor health for the last several years after suffering a series of strokes, a friend of the fighter said yesterday.
"He's been fighting the battle for two years," said Gene Kilroy, Ali's former business manager. "I'm sure he's in heaven now with all the great fighters. I'd like to hear that conversation."
Norton broke Ali's jaw in their first bout, beating him by split decision in 1973 in a non-title fight in San Diego. They fought six months later, and Ali narrowly won a split decision.
Norton won a heavyweight title eliminator the following year and was declared champion by the World Boxing Council.
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But on June 9, 1978, he lost a bruising 15-round fight to Larry Holmes in what many regard as one of boxing's epic heavyweight bouts and would never be champion again.
Norton finished with a record of 42-7-1 and 33 knockouts. He would later embark on an acting career, appearing in several movies, and was a commentator at fights.
Few gave Norton much of a chance against Ali in the 1973 fight in San Diego, but his awkward style and close-in pressing tactics confused Ali and the win put him in the top echelon of heavyweight fighters.