Aug. 17, 1961 - David Susskind, the energetic head of Talent Associates, has signed Jackie Gleason for a leading role in Rod Serling's film adaptation of his own television drama, "Requiem for a Heavyweight." With Anthony Quinn in the title role of the doomed boxer, Mr. Gleason playing his unscrupulous manager and two more key roles yet to be filled, Mr. Susskind expects the film to go before the cameras in six weeks. "This will be the one boxing film I know of," said Mr. Susskind, "where no fight takes place. It opens with the aftermath of a crucial bout, and the battered hero pronounced fatally stricken, after his manager has sold him down the river. By contrast, there's a new, young fighter on the way up - somewhat like 'All About Eve.' Basically, this is a story of man's inhumanity to man."