RE: Crashed in water
You have nothing to loose so try the crock pot method. Get a crock pot from a thrift store(couple dollars) and get some antifreeze. Pour antifreeze into the pot a little more than halfway and fill it the rest of the way with water. Remove the carb and rubber "O" rings and set them aside. Remove the backplate , valve covers, glow plug and muffler and remove any gaskets. Turn the pot on low. Put the engine into the pot along with the metal parts and muffler (but not the carb) and make sure everything is covered with antifreeze. Let it cook for 8 hours and remove the engine and slowly rotate it a turn or two and put it back in and let it go another 8 hours. Then you can remove the parts and clean them up a bit with a brass brush or tooth brush. Oil the engine parts and reassemble it and oil it up again.
You may get lucky and get a few runs out of it before having to change out the bearings.