In the size you are considering, an I/O makes no sense whatsoever. If you could even find such an item, the engine will consume all the space in the cockpit. Maintenance on the I/O tends to be higher than the outboard and, unless you are prepared to remove the outdrive yourself, the entire boat must go in for service.

I have an I/O on a 27' SeaRay and it makes some sense on that size craft where the engine sits entirely below the main deck. Naturally, servicing it.......especially the starter.........is a real PITA.