[dodge trucker]

I have recently acquired a couple of these (finally found some horizontal versions that were quite reasonable)
1 runs good as is, (after a carb swap) one runs but smokes and #3 (the 20 hp) sat outside and the cylinders rusted up. I got it freed up but looking at the tops of the Pistons I can see about half of the top ring so I am suspecting that the jugs on that one will need bored almost for certain. Looking around I don't see much available in oversized Pistons and rings,
Are oversized parts available for them? Even if they're offshore aftermarket parts I guess.
I know that they are a discontinued series of engine from Kohler.