No gas inboard
Hello Frank,3 options:1. Rebuild the original for drastically less cost than a new one. This is a good option if you think you will upgrade to a different boat in the near future, IE: 1 - 5 years. It will greatly help the cost if you remove the engine yourself and take it to the mechanic. This is easier than it sounds (if mechanically inclined), even with the engine mounted under the dinette as in the Cat 30. Consult a repair manual for your engine.2. Install a new diesel, especially if the boat is in good condition and you will own it for many years.3. Hang a Honda (or other 4 stroke) 20hp XL shaft outboard off the transom and leave the dead one in the engine bay. This is the less prefered option however easiest to complete. It will cost about twice as much as your inboard idea.If you convert to a gas inboard, nobody will ever buy your boat. Not only is it not factory original and built to specifications developed and analysed by naval architechts (IE: Atomics in Rangers, Ericsons, etc) but it is also gas inboard, which is frowned upon in the after market. Add to the fact that it is air cooled and likely to overheat in an enclosed bay then you must conclude that any extra money spent or inconvenience had is well worth it.BTW gas inboard andor air cooled may also be illegal. In any case such an installation would have to meet USCG specs - see USCG regulations.