As far as I know, the only supplier of Escape boat parts is George at Mountain Road Trading Post Home
603.895.3501. He is a super nice guy.
I do know that George has a source for the rudders and centerboards for the Rumba. He probably has a source for the rudder head and tillers too, if not, I was looking at my sunfish rudder head and believe it to be a functional match to the Rumba's. Unless the cost of the parts is prohibitive for you, or you just want a woodworking project, I would buy the proven parts and go sailing. I have an extensive background in boat building and fabrication and could easily carve these up but my time is too valuable. Why spend 3-4 hours cutting, sanding and finishing? I'd rather be on the water
I also have a PDF of the Rumba manual if you need it. Send me an email and I'll forward it to you.