all good advice here - I recently bought new Mahle pistons with Goetze rings for my 82 300SD($675 for pistons and $155 for sleeves) after asking similar questions and checking available options. I went for all new and made a variation of a tool shown in Mercedes shop manual to press liners out. One of my liners was very tight coming out as it had hard carbon deposits on the outside of the sleeve(yes, against the basic bore of the block). I'm happy that I did go for all new when I got the pistons and saw that Mahle has improved upon the originals by casting a hardened insert for the upper compression ring. This may be worth looking into. Also, at leathermang's suggestion I called the people at Deves rings and they told me that they offer a ring set with a thicker upper ring (3.17 vs 2.98 they said). Maybe this would be okay for the 616 motor IF the upper ring lands are appreciably worn AND you can get them competently recut to the larger size AND the 2nd ring groove is OK