DIED. WILLIAM DAVID ("BILLY") CONN, 75, boxer; in Pittsburgh, Pennsylvania. In the days when the boxing ring was the central venue for melting-pot rivalries, "The Pittsburgh Kid" was an Irish-American favorite. After turning pro in 1935, it took Conn only four years to win the world light-heavyweight championship, but it's for a legendary heavyweight bout that he is best remembered. In June 1941 Conn challenged perhaps the greatest boxer in history, Joe Louis, for the title. After 12 rounds, the swift and cagey Conn led Louis on points. Then he made an infamous miscalculation--he decided to slug it out. "Of all the times to be a wise guy," Conn later recalled, "I had to pick it against him to be a wise guy." Louis knocked Conn out in the 13th round. Their 1946 rematch occasioned Louis' deathless quip, "He can run, but he can't hide." This proved true: Louis knocked Conn out once again. The two men remained lifelong friends and mutual admirers.