It depends on how well planing board you have and what width at the back. If you have a fairly wide back end at 70cm you will be able to start with 3kw with your weight. A narrow board, then you should dimension for 4kw.
I have a rather narrow board of ~50cm wide and a weight of around 90kg (all up incl. board ~120kg)
maximum Power needed for Takeoff is 2,8kW (60A @47V), often lower around 2kW.
In my experience, the most important factors are the shape of the board (needs to get on plane quickly) the wing used (I use a Gong Curve Pro LT, 1450cm²) and the Prop which needs to fit the motor used.
Believe the closer we are to the take off speed the more impact has the lift of the wing and less of the hull. Stearn always need to be sharp to let the water off easily though. A narrow hull, without a wing, would struggle to plane even at high speed. But as the wing( especially a large one) creates the main share of the lift in such case, even a narrow hull can lift at low speed /power requirements?