I don't think Kaku was on the same level as Jabra. The Douriki measured raw physical strength and was taken before Kaku consumed his devil fruit (this may have raised his raw physical stats). Furthermore Kaku was a swordsman, and a raw measure of physical strength wouldn't encapsulate this.
I guess the simplest way to explain this is that I don't see Sanji beating Kaku in EL.
I expect the gap in bounty between King and Queen to be even higher than the raw Douriki gap. Furthermore, the Yonkou's strongest subordinates have been significantly stronger than their next strongest subordinates (Katakuri - Smoothie/Cracker, Marco - Vista/Jozu, Benn Beckman - Lucky Roo/Yasopp). I expect Kaido's crew to be similar.
What about King's swordsmanship?
I think you mean King here.
I've flirted with the idea of Drake and Sanji tag teaming Queen.
What scene was he talking about? Do you have the source for the original statement?