Can’t go wrong with either Gibson or Koufax. You could also put Randy Johnson into the mix for the start. Not sure about Bumgarner, though.
Re Bumgarner check out his WS record.
His literal record.
Best ERA all-time in WS history. 40 IP. One ER. 0.25 in 40 IP of WS play. PLUS in two single game Wild Card playoffs, two nine-inning shutouts.