We extend to you a cordial "WELCOME ABOARD !" Come on in, make yourself at home, we are a friendly group of enthusiasts, and we also appreciate the classic Chris Craft Roamer, Corsair, and Lancer boats too , as they are all on the same family tree and share much in common ! Just start by posting a note introducing yourself to the group, that's all it takes here (we don't ask for or retain any personal information here, because our intention is to just "have fun and share information".
It can easily be demonstrated that you are installing the "original" motor type and power. It would be the same as if you found one down the street, as there are undoubtedly some there somewhere in the country due to the fact that these boats populated the area and needed work, had motors removed, repaired, rebuilt, etc.
Your boat can be documented to have received a certain power rating. I am quite sure I can demonstrate with original documents from Italy that your boat received a particular type of power in original form. Let me know what you are wanting to do. I can send you a letter, photocopies, etc. and it might help but it depends on how head-strong the local officials are and how they view restoration of vintage boats.