WHen I buy motors etc for my landscape biz, I not only look at what might be the best, but mostly, what is the availiblitiy of parts and service etc. For this reason alone, I would probably go with a Yanmar, only as my gut says it might have a better parts/service/warrenty options outside NA. I could be wrong on this, but that would be my first choice. As also mentioned, it would be a non turbo motor also. Most folks that I know that are repowering older boats with turbo's are going to non turbo equals. One more thing to go wrong, and more power off the line with a non turbo motor too!
You might also look at bumping the HP up say 5-10 also. This might allow you a bit more go power if the going gets rough, ala currents, wind/waves and a lee shore. If I redid my 16HP Yanmar, I would try to go with a 20 if I could do it in the same 2cy 2gm I have. I would not go to a 3 cyl to succeed personally.
She drives me boat,
I drives me dinghy!