The Giants didn’t have to reach far to find a successor to longtime pitching coach Dave Righetti. The club will add former A’s pitching coach Curt Young to its major league staff next season, sources confirmed. The Giants are planning a Monday announcement to make official the hiring of Young along with new hitting coach Alonso Powell, the former hitting assistant with the World Series-champion Houston Astros. Young and Powell would join new bullpen coach Matt Herges, who was most recently the pitching coach with the Dodgers’ Triple-A affiliate in Oklahoma City, as three new faces on manager Bruce Bochy’s staff. The Giants have almost completely turned over their coaching staff in the past two years. Changes were expected after the team entered this past season with a payroll near $200 million yet matched the Detroit Tigers for baseball’s worst record at 64-98. Young, 57, has been out of a job since the A’s fired him this past June. He has served two stints as the pitching coach in Oakland, first from 2004-10 and again beginning in 2012. He served as the pitching coach with the Boston Red Sox in 2011.