Scott,

Awhile ago, after seeing someone here post his copy of the original
bronze shaft and Honduras plank rudder,

sent to Bill, our Leader, an ebb upgrade for building a new traditional
rudder. It uses the original plan of internal rods anchored to the shaft.
BUT
In my opinion the method is far easier and cleaner than the original.

Maybe you can wheedle a copy from Bill?

Your friend, Ebb