Just a thought... maybe you could swap your engine for one from a tractor someone unwisely added a loader to. The place where they break wouldn't matter much to a 154, since it has a frame, and there is very little strain on the weak spot. I know many have replaced otherwise good engines because of the crack that is ALWAYS weaker after a repair.
I have a 154 here that was the engine donor tractor for Rambo and I'm considering offering it along with a rebuildable repaired engine... it would make someone a good project at a good price.
Before the engine was removed:
The repaired block came from the world famous "Scruffy".