It would be very interesting to see what, if anything, Honda did to this engine when produced for their outboard marine application. Marine use is similar, I think, to aviation with max power to get the boat up and planing then continuous high power application at cruise - particularly if used in a ski boat. But, I doubt any non-competition use is as testing on an engine as an aviation application.
The marine versions are under square ( longer stroke, smaller bore) than the car engine which should flatten the torque curve. It seems Viking are using the outboard crank rods and pistons. All good for constant throttle ops.
cheers John