So I am a nut about my rudder system. This is one of my tricks I was tinkering around with fine tuning tonight and thought I should share.
Don't fill the old hole with epoxy. What you are looking at is some Aluminum stock fit in an oversize hole, nothing to it. It wears better/works smoother than running the bolt through fiberglass. If you wanted to get really crazy brass or bronze would also work great. Use a Forstner bit in a press if you are afraid of the old hole causing the bit to walk around.
Drilling the hole in aluminum off center allows really fine tuning the adjustment, even within the new adjustable systems. I have found you can play around with the exact positioning of the hole in the rudder, and once set perfectly it GREATLY reduces the effort required to lock and unlock the cams as you can really adjust the angle the the depth at which the latch strikes the cam.
Oh.. and setting rudder rake.. Lots of people use that whole measuring off the line made by the pin.. whatever.. What I do is measure from the lower corner of the transom down 12 inches.. Make a mark on the rudder, then measure 24 in on the boat. Measure b/t those points and set both sides perfectly the same that way.. MUCH more accurate.
You set that by adjusting the Allen set screw in the lower casting for a perfect stop point.. THEN go back to upper casting. Push the adjuster latch most of the way forward and try and lock it gently with the adjustment bolt just tight enough to slip back.. This holds the rudder as tight as can be to the stop and also makes it smoother/easier to latch and unlatch..
Once you have sailed it and are happy with your adjustments.. Place some plastic/Saran wrap over the uppermost leading edge of the rudder( or coat with Vaseline, whatever) Then fill the lower casting at where the rudder meets with Silicon... Lock the rudder down and let it dry.. Then remove the plastic wrap. This will make the rudder fit very nice and tight with a bit of extra support in the locked position, and prevent maladjustment due to wear or the set screw moving around.
Least that is how I do it.