The Norton 8k is tough to beat, and I have been looking.
I use a Nubatama 1 & 4k, Norton 8k, Naniwa Super Stone 12k and GS20 or natural finisher.
So far that is the best progression I have found. My 8k is getting thin and will probably replace it next year with a new Norton 8k, or Shapton glass.
Never used the King 8k, but have an old King/Ice Bear 10k that was my finisher for many years, before I bought my pink 12K SS. It is almost as good as the 12K Super Stone.