As the rudder is a flight control, repairs or modifications need to be taken seriously. Sleeving the rudder post would probably be considered a major repair or modification. This would require approved data for a form 337, probably from a DER. And, only the installation of a rudder manufactured from 4130 steel would comply with the SB. It would likely be more cost effective to just purchase a new rudder manufactured of the required material or make an “owner supplied” part than try to get the modification approved. I do not believe that you could drive a repair sleeve up from the bottom without damage and coming down from the top would also require opening up the rudder. How you would ensure that the adhesive remained where it was supposed to? If I was even contemplating a sleeve type repair, I would remove the fabric and check for pitting and/or cracks. If all was pristine, I would sleeve the rudder post and secure the repair sleeve with rosset welds. I would then epoxy prime inside and out before I recovered the rudder with fabric. It would not comply with the SB but I would know that it should never have an issue at that hinge line attachment.
Merry Christmas to all!
N2709P