Steve,
Welcome to the forum. I believe you might be the first person on the forum to own both an E23 and an E25 simultaneously. Your right. There is not a lot of traffic on the forum when it comes to the E23. Bob in VA, one of the persons who posted a response to this thread back in 2007, is the go-to-man for the centerboards. He recommends against building to original specs, which makes sense in many ways. You can, though, build to original specs if you measure the original carefully and rebuild accordingly. I've did this myself in the fall and have completed everything except pouring the mold and glassing. When I get it all finished, I plan to post pictures of the many steps I took. The pictures from the E25 owner JMPirate provided some inspiration. I can say that I'm glad I demolished the board and started all over. After I bought the boat I removed the cracked board. Did some grinding on it and planed to patch it up, but ended up putting it aside while I worked on other things on the boat (an also things on my house) for about two years. In that time, as it sat in a dry, temperature-controlled environment, it degraded even more. The splitting continued until it was distorted. When my buddy and I tore it up with chisels this past fall I was really surprised to find that despite two years drying time, the steel was still wet on the inside. Moreover, there was almost no steel left in the vincinty of the pin. This meant that the pin was supported only by about 1/2 inch of foam and a thin layer of glass. This is, no doubt, why others have lost their boards.
Regards,
Roscoe