The KT66 sits at the same impedance as the 6L6, yes.
You can look at some online specs here:
If you look at the Class A S/E (single ended) and move over to the Zout, you will see the impedance for the 6K6 is 9000, and the 6V6 is 8500 where the 6L6 is 4200. You would want to run a 6K6 at the 6V6 position.
I’m not sure what you mean by what tubes were used, do you mean brand? If so, I don’t know what the brands were.