Been there with my C-27. Drill a few more holes around the circumference. If it's dry you should be good. Patch the holes with expoxy and put an
epoxy barrier coat over the whole thing. If the rudder starts getting play in the post you'll feel it under way through the tiller. If in doubt, call Catalina Yachts. They still make rudders for the C-27. Mine has a replacement from them.