It looks very similar to the Danish HM II, which was a Heinkel He.8 seaplane designed for the Danes. This one is plan pl-729 from 6/78. 63 inch span. A buddy and I were thinking of scaling it up to .90/1.20 size with some foam core floats.

Both planes appear to have good moments, nice long fuselage, so they would more than likely be very aerobatic, even with floats. Here's the photo from the RCM plan page. The Danish planes were painted red, as in the photo, silver and camouflage.