Hey Roylo,
I currently have a 4.65m plate boat approx 800kgs for the boat,motor,fuel and 2 guys. I am running a 4 stroke high thrust 60hp Yamaha and I am getting 26 knots wide open out of it, not sure what the km/h conversion is. Obviously different props could increase or decrease this top end but that is at 5800 rpm and it still gets up on the plane quite quickly. It's not exactly what your looking at but may give you an idea of what you may be able to expect.