I was refering to a couple of the local fliers with their choices. The Beaver is good in that you can put in a heavy engine and still not have to worry about it being nose heavy. I know the Irvine 120 powered one required a fair amount of ballast but I'm not sure how much. My Saito powered one is still being assembled so I'm not sure where it will turn out. Another one around here has been flown with a Saito 180 and it had lots of power. I'm sure a well set up Beaver with a good 90 or 108 would fly well also. Use a prop in the larger diamerer and lower pitch range for your engine to get lots of thrust for take off and also to provide some braking for landing approach.
Personally I would stay away from salt water with any plane.
Be sure to refer to some of the earlier posts regarding float set up as what is provided is geometrically incorrect. It will save you lots of headaches.
Merry Christmas,
Peter