With the floats on, I am using a .70 four stroke. There is no such thing as overpowered IMO. There is such a thing as using to much power. When you get into 3D flying you will need to understand throttle management any way. That style of craft is designed with large control surfaces that will likely flutter if you are making full throttle high speed runs. As long as you can balance the plane without adding loads of weight then the engine is probably OK. Just make sure you are throttling back before you dive and it should be lots of fun. Jeff.