Teeing off from the white spot, Manibusan launched it over halfway to the green to have an early birdie putt in the first hole.
He had more birdies in the following rounds to secure the lowest gross.
Placing second was Nick Sablan who shot 7-over par 79.
Jojie Tagutchi and Jeff Taylor tied in 80, while Jess Wabol, Steve Balakrishna and Adam Hardwicke had a three-way tie in 82.
Meanwhile, the coordinating committee for the Micronesian Games golf qualifier has decided to go an extra round.
From an original five qualifying rounds, the qualifier will now have six rounds, plus a possible make up round.
The first three rounds including that of last Saturday are teed off from white while the next three rounds will be swung from the blue.
The qualifying round will be on April 17 with time and venue to be announced later.
