I found a combination that is in the ballpark of the custom PTone mix I used before, but not really like the straight previous WN set. Basically no matter how much you play with the Carbon set mixed into the WN set, you never quite reach the chroma of the original set. I finally let that go, and settled on something appealing rather than insisting on a dead match. Here it is as a quad set-
WN shade 5 60%
Carbon shade 5 40%
WN shade 4 56%
WN shade 3 24%
Carbon shade 4 20%
WN shade 2 70%
Carbon shade 2 30%
but this was to try and approximate a match to a legacy quad set that was Piezotone WN with some carbon mixed into all but the mid ink, which was gorgeous as it was, I just liked the highlights and shadows a hair less olive. I doubt this helps… extrapolating this out into a K7 set might ba a pain, and it’s still not intended to match the original WN. You’d probably want less Carbon mixed into the shadow inks, the originals were pretty olive in the shadows, there was a subtle split.
The above is one half of my existing dual quad setup… the other half is a quad Selenium set cooled a bit with some from the neutral set.
Sorry I can’t be more help… I finally decided one has to just move on, find something you love with what exists, the new inks are superior inks anyway and everyone here including me is happy with the result, I just needed to continue with a variable set…