Thanks for all your help so far. I am ready to order parts for this conversion and know where to get them.. In the mean time, I want to replace the water pump impeller and do a general tune up of ignition, cylinders, etc. Does anybody know where I can find repair and parts manuals for this 25 HP 1953/54 Evinrude Big Twin? Can’t find anything prior to 1955 on Ebay or elsewhere.