Your motor is a 1974. Looking at the parts list for a 1975 25hp electric start, I would guess it probably is possible. But you know how reliable guesses are. Try http://franzmarine.com/
If your engine has the verticle starter with the pinion gear,it can’t be converted.If it has the top mounted starter, it uses the same ele.starter as the 25 and 35 of the same family.I hope this helps. Bill