I think regular bearings are fine the prop will pull 25 lbs tops if it’s balanced. There will be no up or down movement. If it’s a cog belt there will be very little tension puling down. They can’t be very tight or they will fail. Even bronze bushings will do. But you will have to grease on a regular basis. The shaft will only turn at 3000 rpm no faster then an electric motor. I think a lot less stress then the bearings in the engine that are under heat, and 3 times faster.