Contemplated the same thing on a 25HP I had several years ago. Thought it would be easy. Well, I called Johnny (can't remember his last name) but he had a repair business in S. Houston and taught marine mechanics at San Jac Junior College. He said you had to have an automatic choke and a few other items that would make it difficult. I sold the motor and found a 35HP with elec start. if you are h..l bent on doing it, I would talk with Jack Stone at Stone & Sons Marine and see what he thinks. He has tons of parts and old motors to pull from.