The 1 cylinder marine diesel has been identified as a F-M 45 or 45B.

The guy in Florida would like to see it go to a collector rather than to the scrap yard.  I don't know what that means price wise.  Can't say that he'll give it to you or would want scrap price for it.  That's between you and him.

The engine is at Jacksonville FL and I assume would need to be picked up there.  If you are interested in the engine and can pick it up let me know and I'll give you the contact information.