D&R Marine still makes rudders for specific ODay models, not sure about center boards. Try calling them, Rudy is super nice and would have the specs if anyone does.
Don't email him- he's pretty much a solo operation, and will call back, or if you're lucky will answer.
You also probably know, those ODays did not have swing keels, but rather an unweighted board. It probably weighs around 70 lbs.