IMO, going into a 3 or 4 game series, I would start Koufax ( he could go 9 innnings again on 2-3 days rest), game 2 go with Rocket, and close the series with Fernando.
If a game 4 series, come back with Koufax.
The object being to win at least 2 of the 3 games, and keep a fresh short bullpen.