Don, welcome to the forum. Great adaptation! The old Classic is a fun boat and I always wondered how it would take to sailing. How does the helm balance feel -- does it have a tendency to head up into, or bear off from the wind?
The Turbofins turn the Classic into a little hot rod, besides giving you a little more "centerboard". Stringy
has made a "Twist N Stow" adapter to the old rudder system that is really cool, on which he mounted the larger rudder; and Kepnutz
made an excellent rudder sleeve with winglet that fits right over the original. Both sail their boats and report the larger rudders make a big difference.
Check through their postings to find their projects. Too Bad we don't have a "How To" section.