Mercury 60HP American Outboard Federation Motor Project

[rustnrot]

Here are some pics of a recent motor I could not pass up that obviously has raced before. I need some advice from this fine forum.

1. What is (was) the American Outboard Motor Federation
2. What class would this have raced in?

It is to the best of my research, a 1989 Mercury 60HP short shaft with factory tiller (it is hardwired in). It would be a 49.9 cu inch motor with 1.64 ratio gearcase. It has WM-11 carbs which if I researched correctly, would be for a 70HP motor. You can see where somebody did some grinding on the exhaust. It has some scoring on the top piston so advice needed.

Rebore and new pistons all cylinders? Keep the 70HP carbs?