Might catch some flac for this, but this is what I would do if it was made legal for a K circle boat. Pick the appropriate blower, mount it on the back and drive it off the crank/flywheel side 1 to 1. DEFINATELY lighter and would lower the center of gravity in the boat (better for turning) and would likely make more power. I know it's not typical, but it would work!
Hey that's messing with nostalgia and we can't have any of that.
Next thing someone will want to run EFI and that will be the point of no return.