I replaced the stock rudder set up on my Mystere 6.0 with that of a Prindle 16/18. They worked better than the stock rudders.....until one snapped sideways (rudder and casting both) when a swell passed under me at sea. I'd recommend giving it a try. After all, it is a simple un-bolt, re-bolt blades only, swap-over isn't it?

By the way I have never regretted the breakage because it was the heart of a fantastic adventure/story.

I'll bet your trouble with heavy helm can be solved with tuning.

Gary