Alternate the ring gaps so they dont all line up in a row. this will assure good compression. Lubricate w/ motor oil the rings, wrist pin and bearings when you reinstal. Make sure the ring compressor tool is lubed along the walls where the rings slide through. Do not pound the pistons out or in. Light tapping should do with the bottom of a hammer (the wood part) or a dowel.
I doubt you will need to rebore. Can someone else in this forum comment on the need to hone the bores with a drill mounted honer? I recal when i reringed an engine I honed only enough to break the glaze and set up the correct cross hatch pattern.
1982 300D Turbo