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".
Sorry to hear about the Detroits. They are robust engines to say the least. I ran a 671N for an entire summer thinking I just needed rings. When I tore it down, pieces of the lower half of one of the pistons was laying in the oil pan!
The Cummins are a good find. There was a 1980's 42' Commander out here in California that had Cummins 450C's in it. I seem to recall it achieved the numbers you are anticipating. Hey if you really want to get into it, there are the QSM11's, but then again I tend to over do things. Looking forward to your next post.