Based on our own experience, going with the Catalina factory replacement is the way to go. Much less expensive, particularly if you can pick it up yourself, as we did. Given the age of your boat, and the amount of water you found in the rudder, it is doubtful that the steel core is in good condition....perhaps still good, but very doubtful. As for getting the "new" shaped rudder, it does make a noticeable difference. Having said all this, if you can handle the glass work, and have a source for the ss material and welding, it would make for an interesting project. Please keep us all posted.