I have an update for everyone on this. I attempted to bore the original sleeve on that broken piston's cylinder and the scoring was too bad for it to clean up with a 0.020" (0.5 mm) over bore. There's no 0.030 or 0.040 over pistons available for these, so I bought a rebuild kit with new sleeves and standard size pistons and rings for a Kubota DH1101 (also compatible with D1100, D1101 and D1102 Kubota engines). Upon assembly with this kit, the only part I've encountered so far that hasn't worked is the valve seals. I ended up using valve seals from an early '90s Ford Taurus 3.0 V6 (the Vulcan pushrod engine, not the DOHC Duratec) which fit perfectly. Right now I've got the bottom end assembled, the head is on, cam is installed, crank and idler gear are on, and I'm just about to install the injection pump cam and gear. I'll probably wait to give another update until I get the tractor running.
So to review, the cylinder liners, pistons, rings, wrist pins, wrist pin bushings, rod bearings, main bearings, and so far all of the gaskets specific to the Kubota DH1101 also fit the Kioti DH1101. The pistons look like they were cast from the same mold. They are absolutely identical to the originals. As I said above, this is great news for both these early Kioti tractor and Kubota L245 owners because it gives a cross reference that allows a broader pool of cores to be used for things like engine blocks and cranks, and guys needing to re-sleeve and overhaul LB2204 engines can just get the Kubota parts. Those L245 engines are unicorns and very expensive to get cranks and blocks for. You can probably buy a whole LB2202/04 in good running condition for less than a complete running Kubota DH1101 engine by itself. The market for Kubota parts reminds me of old Mopar stuff. I hope this helps some people get their tractors running again.