FWIW and IMHO (LMAO),

TWISI (The way I see it) You have been given some excellent advice by some pretty experienced people.

In no particular order that excellent advice includes:

If you are happy with how it runs - don't worry about it

If you are worried about the time taken to get a good ring seal, Get a Frank Bowman Ring

It will take a long time before the Chinese Ring fully beds in

All the above is excellent advice But some of the best advice is

DO NOT Run the engine excessively rich.

Tune it for best top end RPM and decent transition. IF you feel uncomfortable with the needles at the best RPM setting and really want it to be a little richer, open up the high speed needle by about 1/16th of a turn (about a screwdriver blade width) for your peace of mind.

The DM 55 is actually not a bad engine for the price but they do have the "Classic" Chinese rings in them that never want to wear in fully, especially on the flame chromed bore it runs against.