Any of those 2 stroke engines would work fine. It really depends on if the engine runs good and is reliable, not flaky or tempermental.
For a 4 stroke you need to up the displacement some as the 52 four stroke would be too anemic. Years ago I used a Saito 56 on a seaplane and it definitely was under powered. The floats add a lot of drag to the plane, so you need extra power to compensate. I would go with a 4 stroke of around 70 size in displacement if you go that route.