I have a 18' Silver Streak Challenger. Put a 140 Suzuki on it in 2014. Great motor and performs well. Cheap on fuel, nice and quiet.
Would never choose a merc over a Suzuki. Lots of the guides on the west coast use zuki. Just my opinion of course, but the guy to talk to is Gord at breakers in Bamfield as Trophywife has stated. Your money but at 11,600, that's a good deal.