West gained the lead, Ben Hunt and Tony Rawstorn settled into second, with Matt Jansen and Grant Marra clinching third.
"It was a bit of a battle and I'm pleased to get the win," said West.
"Richard hit a rock that caused his puncture and we also hit rock in the same stage about three kilometres in. It could have been the same rock and it bent our steering so we really struggled in the run to the finish and so winning the stage and rally came as a surprise."
Fans were out in force to see some of New Zealand's big names compete over the gravel roads of the region for the first time since 2000.
Light rain made conditions damp for most of the day and the 41 teams who made it across the finish line had smiles of relief on their faces. The hard surface and flat-out flowing style made for a rapid journey and West didn't think he could eat into Mason's 18-second lead.
However, West was surprised to learn Mason's time was six minutes longer than anticipated, handing the win to the Timaru-based driver.
"It's certainly the best result we could have hoped for and really helps us for the next round next month at the Possum Bourne Memorial Rally.
"We had a new car at the start of the season and it's taken awhile to find that sweet spot of a perfect set-up. We've improved at every event we've been at this year and are getting better and better."
The points at the top of the table have tightened considerably and, with two rounds to go in the championship, things are sure to get interesting.
Mason's recent two bad results have opened the title race and any one of four drivers are in with a chance.
"Obviously with Hayden [Paddon] returning to race, he's going to be the benchmark for the rest of us," said West. "It will certainly change a few things, which is good for the championship and should make the end of the season pretty exciting."
Hunt's second place at the event, combined with his other podium finishes this season, has elevated him into the series lead, albeit by just one point.
"We were happy to be as high as third, so to finish one better in second is fantastic - considering we hadn't had fifth gear since the second special stage of the morning," said Hunt.
Deane Buist and Andrew Bulman won the 2WD category in their BNT Historic category Ford Escort RS1800. Finishing ninth on the day, ahead of current points leader and fellow local driver Jeff Judd, Buist closed the gap to now trail by just nine points.
A season of tit-for-tat between the latest R2 specification Ford Fiesta cars of Phil Campbell and Josh Marston fell Campbell's way. He now leads the class by 12 points.
Matt Summerfield was among those unlucky to finish. His day ended on the second special stage when he left the road.
Emma Gilmour's new-generation Suzuki Swift had a blown head gasket, which caused the engine to overheat.
Alex Kelsey retired after a drive shaft failed on the fifth stage - the same piece of road that claimed championship rookie Taylor Jansen.
NZ Rally points
1 Ben Hunt 89
2 Hayden Paddon 88
3 Chris West 77
4 Richard Mason 66
5 Matt Summerfield 35
