Howard Johnson will be named hitting coach of the Mets on Friday, getting the nod over Rickey Henderson, who will coach first base, baseball sources said. Ninth in the National League in runs after finishing third in the NL last season, the Mets fired hitting coach Rick Down during the All-Star break and interviewed Henderson in San Francisco this week. GM Omar Minaya decided Friday morning that Johnson, who managed and served as hitting instructor in the Mets organization before being named the parent club's first-base coach before the season, would be best suited to replace Down.