Well, that sent me down a bit of a rabbit hole of trying to find pictures of the rudder on the 26 (and not finding one), and after that, my answer (based on pure speculation) is most likely no. From what I recall the first few boats Ericson built were either re-branded/re-badged designs from other builders, or like in the 26-1's case designed by Crealock vs most of the later boats by Bruce king. So, it is unlikely that a rudder for one of the later boats would be a direct replacement for a rudder on yours. You may be able to find something close and then modify it if you have the skills.
That said, most rudder builders can build you a new rudder that is based off of the design of another boat but adjust it so it would fit yours. For example, the upgraded rudders that were designed for our boat, are also direct replacements for a few other very similar designs, but also the very different Cal 40 and I think I've seen it on one of the larger Ericsons as well.
So, long way of saying that an new upgraded rudder is very possible, but a direct replacement from another boat is less likely.
If it were me, I'd try to learn what situations the boat is becoming uncontrollable in and either avoiding them, or understanding where the line is and see what adjustments can be done to keep things under control. Often it's too much sail area on a particular point of sail and yes, a deeper, higher aspect rudder could help, but it's a lot easier to reduce sail area or head up or down a few degrees to put the boat back in it's comfort zone.