On my main computer, not the dog and bone
First 2 photos are the bottom socket thing with the Novasteen bushing, which the boat yard replaced in my 2016 antifoul period. The 3rd photo is the bottom of the keel, where that thing came off from. 4th photo is the bushing where the rudder goes into the cockpit, and you have the cockpit photo and tiller thing from the Compass forum and my post therein.
When I did all this, I collated all the notes posted in the C28 forum about the topic. From these notes:
3 Delrin (plastic) bearings 1 at the bottom and 1 at each end of the tube. I expect these are 1 1/4" long by 1" bore by 1 1/2" +5 thou interference fit OD. A machine shop with delrin could turn these up. Getting the rudder out, get a profile shot of a C28 and speak to the boatyard you should be able to do it if the boat is far enough forward on the cradle and with about 20" clearance below for the rudder to slide forward and down. Even easier off a travellift. The C28 rudder has no water seal and the best indication of worn bearings is cockpit flooding at high power settings
I can answer for a C29. The shaft OD is 1.000 ". The rudder bottom pintle is also a 1.000". and the bush in the cast bronze fitting that positions the lower end of the rudder is a sintered bronze bush ID 1.00" and OD 1.25" length about 1". I increased the bush ID to a clearance of 0.006" by using a emery flap wheel in a drill. You should accurately measure the OD of the pintle to set the clearance. The bronze fitting was held in place by two copper rods that were peened at each end. I replaced these with type 304 SS bolts Dia 5/16", penny washers and nylock nuts. The bolts lengths were 3" and 3 1/2" due to the taper in the bronze casting.
"Some plastics swell in salt water (Delrin and especially nylon suffer from this problem). Dimensional changes of up to 6% have been responsible for a number of siezed or tight systems." He recommends something called UHMWPE (ultra-high molecular weight polyethylene) Incidentally I came across soem words of wisdom in a Nigel Calder book.
That's the relevant parts. My experience you read in your link "removing a Compass28 rudder" also summarised the process.
Any competent boat yard with some people to weld stainless steel will be able to do the job; you just need clearance or to remove the rudder while in the travel lift.
Good luck
