Not a mag dk myself, so i cant really advise rotation, but you probably want to drop infal for something else. Its not really 'meta' anymore. I hear its fairly difficult in practice to hit high on a dk (they have all the tools, but hard to sustain) if your hitting 36k id say your on the right track. Keep Zaans, but update your other 2 sets. Bsw will always be good but there are better options available these days.

For most classes, good is as anything above 42k, and great is above 45k on (3 and 6 mil dummy not trial). All classes can reach these benchmarks. Other than updating gear you should research cp distribution and really take time to understand all your abilities and passives and how they work together. It will really help your rotation. Last but not least, practice animation cancelling/weaving. Being consistent with this and improving it while difficult can easily net you another 10k.