I don't know anything about this Engine but I remember when I was in Trade School (about 1975) on a Mercedes Engine they found that the Pistons measured out as still serviceable.
They bored out the Block and pressed in generic Sleeves (there is catalogs with different size automotive Sleeves and Sleeve materials).
I can't remember but I am guessing they used Sleeves with a Flange/Lip on the top.
At that time oversized Pistons were available but were too costly for the Owner so they bored, and sleeved it, and bored it again to the Standard Bore

This is the same as they used to do with Gasoline Engines when the Block was already past the last oversize; sleeve back to standard size and start over.

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84 300D, 82 Volvo 244Gl Diesel