Thanks for replying.
You're right - I want a 2-blade prop. I'm trying to do this as inexpensively as I can.
It's a RH prop. I'll measure the shaft tonight.
She's currently got a 14-10 as well. However, wide open under load I can only get 2500 RPM. My mechanic says that's due in part to having the wrong prop on there. He suggests a 12-12 or a 12-10. I've run the math, but my results are dubious at best, so I was casting about for a more experienced opinion.