Question: When did the heavyweight boxing championship match, for which the Zaire 74 concert was intended to be a major promotional event, actually take place?  
Sentence (from "Zaire 74"): The concert, conceived by South African trumpeter Hugh Masekela and record producer Stewart Levine, was meant to be a major promotional event for the heavyweight boxing championship match between Muhammad Ali and George Foreman, known as The Rumble in the Jungle.
Relevant evidence: Yes