Often, learning the architecture of obsolete Kubota engines can be challenging.
In general, all Kubota Turbo engines will be Direct Injection, with the injectors centered on the bowls in the piston tops. Non-turbo Kubota engines are usually Indirect Injection, with the injectors delivering fuel to a small spherical pre-ignition cavity that opens into the combustion chamber. And, no bowls in the piston tops.
If you look at the gasket surface of an IDI head, the port from the pre-ignition chamber is readily visible, and you won't see any place where an injector could be placed to deliver fuel directly to the combustion chamber.
It seems likely that crank and rods could be interchangeable between engines with the same bore and stroke. Does anyone know if you can put bowled pistons and a DI head in/on a non-turbo short block without complex machine work? I kinda doubt it...
-Paul