I suspect the sleeve moved down, the piston caught it, but instead of pulling the sleeve down, and taking out both rods, it just broke the rod at the crank journal, which clears the rotating parts of the engine. Like Bert said, you are basically done at this moment. There is most likely a Kohler Command conversion available if you want to spend the money and put in a new engine.
The Triad engine used what is called lost foam casting technology. the upper half of the crankcase, the intake manifold, and heads are molded as one piece. Because of this setup the cylinders had to be bored from the under side of the crankcase and then the sleeve pressed in. So when the cooling fins of this engine would get clogged with various foreign materials like grass, mouse nest, etc they would do the same thing that the briggs does to the valve guides in the heads when they overheat. The aluminum expands more than the cast iron and looses clamping tension and then they start moving.
