To make the rudder stops, we started with stock 1” x 1” x .125” 6061T6 aluminum angle. Cut it a little longer than 3 inches so you have extra material to grind the appropriate angle.
Drill out the 1st and 3rd rivet and match the holes to your new part.
Test fit and check to make sure the stop and rudder horn mate evenly. Next step is to make one for the other side.