I think it's base Kaioh, as in the scene right after Juukei's statement
Kaioh's matouki tears a hole through his armor, clearly implying that the Kaioh Juukei is refering to is the same we're seeing.
I'd argue that 30% pre-seals Ken already scales to the Multi-Continental statement, as it's stated that
Kaioh's matouki was being amped by his hatred of Hokuto, and
Ken straight up tanked a matouki strike while at 30%, suffering relatively low damage. Let's also not forget that Ken was being havily chi-drained throughout the whole thing
I also wanted to talk about this concept of everyone related to Hokuto having Tentry Kokyu Oh, well, they shouldn't, it's expressly stated to be an Hokuto Shinken only technique and no non-Shinken Hokuto user has ever displayed it. During their second fight Kaioh is stroger simply because he gre stronger and was in a place that amped him