New rings may be sufficient if you still see the original cross-hatching everywhere in the cylinder. If not, the cylinder may be too worn to just "hone". It may be worn oblong. In gas engines, one then generally bores the cylinders out to the next standard size and buys new pistons and rings. But that is not possible in our engines because there are no over-bore pistons available and even the std size are currently not affordable ($500 each!). For a Chevy small block, you can get a set of 8 pistons for <$100.

But, we can actually do better. The OM617 has cast-iron cylinder liners that can be affordably replaced. I removed mine by just driving a flat screw-driver from the bottom between sleeve and block, which easily rips the cast iron sleeve, then just slide it out. Installing the new ones is harder. I heated the block and chilled the new sleeves, but still needed to rap a sledge hammer on a steel plate above to slide each one down. The sound tells you when they seat on the upper lip. But be careful since they can easily crack. Then, a shop machines the sleeve bores to match each piston. You need them fairly close so you don't get "piston slap", which is common if one just re-rings and the bore is too worn. Of course, all is more critical in a diesel. The result is well-matched pistons and bores, with bores back to original spec.

BTW, unlike gas engines, very few here have rebuilt a diesel and seems very few shops do it, and none affordably that I have read. If you do so, you will be a hero at a young age. One guy here a year or so ago posted similar and seemed a bit naive, but then finished in <1 week and posted photos. They were on a remote ranch, but had machines for decking blocks, honing, and all. Amazing post that you should search for.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans