They won't fit the older 16's helm. I had to make a really custom one for mine. They fit any of the stock helms that CD uses that have the black plastic cone looking hub insert. I don't remember the name brand of that helm, but they are used in Bayliners and other boats as well. The hole that it fits into is 2 3/8".
Koa. I would need a piece a minimum of 1" thick (1 1/4 would be better) and a minimum on 3" sq. Send me enough to do two so I can make on for me also. I love the look of Koa. I can switch off every other month with the Cocoboa Rosewood one I have installed now. But to answer your question, I would love to make you an replacement helm. That is JUST in case you buy a certain 25 that you have money on and can't wait to find out whether it is a go or not. Just in case.