Ruangkit went wire-to-wire to finish at 11-under-par 277. He became the fourth international winner in the last five years and the sixth overall.
'John Jacobs is like a big brother to me and I watched him on television, playing the Champions Tour for many years, Ruangkit said through a translator. 'I saw how successful he was over here and that motivated me this week. I really wasn't aware I was tied at one point today. I just played my own game and wanted to do my best.'
Ray Stewart shot a 3-under 69 and took second place at minus-8.
Rod Spittle, who caught Ruangkit on the back nine, only managed an even-par 72. He tied for third place with Bruce Vaughan (67) and Doug LaCrosse (71) at 7-under-par 281.
Ruangkit, a five-time winner on the Asian Tour, started with a five-shot lead on Saturday, was even par through 12 holes thanks to one birdie and one bogey. He dropped strokes at both 13 and 14 and with Spittle being four-under on his round up to that point, the pair was tied.
That did not last long as Spittle spit up the lead. He double-bogeyed the 16th and bogeyed 17 and 18 along the way to the clubhouse to fall into a share of third place.
Ruangkit still struggled as he bogeyed the 16th, but a birdie at 17 preserved the medalist honors.
Robert Thompson, who was alone in second place after the third round, struggled to a 4-over 76 on Saturday. He tied for sixth place with Perry Arthur, who only managed a 3-over 75, at minus-4.
John McGough (75), amateur Graham Banister (74) and Harry Taylor (73) shared eighth place at minus-2.
The top-30 players and ties earned a chance to open qualify for full-fielded events next year on the Champions Tour. The score ended up being 5-over-par 293 and 33 players earned spots in weekly qualifiers.
The biggest moved on Saturday was former Champions Tour member, Pat McDonald. He only shot a 2-under 70, but it was enough to move him up 28 places into a tie for 30th.