Ericson 30 needs rudder parts

Hello i just bought a 1968 Ericson 30 and she needs to have the rudder put back in. I have the rudder the tiller and the shaft that comes out of the rudder itself. dont have anything else. I know of someone pulling out a 1972 Ericson 29 that they plan on scraping. does anyone know if the internal parts are interchangable. Does anyone have any suggestions at all about how to go about this? any advise would b great