Converting a straight inboard to a jackshafted I/O outboard I think would be a very difficult project. The inboard seacraft has a prop pocket or "tunnel" where the running gear /prop sits. If you look take a look at either Craig Miles or Capt. Skip's inboards you can see the half moon curve of the tunnel which runs from the transom up approximately 1/3 of the way up the keel. The bottom of the v of the keel is in reality "missing" as this is where the shaft /rudder/skeg sits. I would think that this tunnel would create cavitation which would prevent either an I/O or an outboard from getting enough clean water for the props to get a good "bite" on the water. However, like the saying goes "anything is possible" and I guess it could be done with a a huge amount of hull modifications.
If your looking for a jackshafted seacraft, they do in fact exist, however, they are as rare as hen's teeth. A while back I believe there was a thread called "seacraft trivia" and if I remember correctly Trayder posted that the number of jackshafted I/O Potter seacrafts numbered in the single digits (3 total?).
If you are determined to undertake such a major project, it would seem to me you would be better converting a hull that was all ready an I/O and figuring out how to move the engine forward under the console.
However, as a wannabe seacraft inboard owner I think it would be a crime to convert a straight inboard into either an I/O or outboard.... [img]images/icons/shocked.gif[/img]
edit: you can see the prop pocket here:
http://www.theboatzone.com/gallery/miles01
[ February 19, 2003, 09:37 PM: Message edited by: deepsushi ]