This is all great input. Thank you! Getting rid of the reduction gear would make engine fitment easier, but it's looking like reduction is necessary for the props (probably larger props)to run efficiently. The Borg Warmer manual does say not to use reverse gear to compesate for engine rotation. Whether I could get away with ignoring that advice is still an open question in my mind. Isn't that how they did it in the '63 with 6.2 diesels?