There are a number of used parts guys out there and you can also place a wanted ad on AOMCI.org. I would recommend contacting Doug Penn (Douglas.Penn@gmail.com), who is a dealer in antique and classic outboard parts. If you google his name, you can go to his website. I know he has Handitwins in his personal collection and may also have some parts motors. I deal with Doug regularly and he is fantastic, and his prices are very reasonable.