George William Herbert wrote:

There has to have been some error there; the J-2s were LOX/LH2
upper stage engines, not lox/kerosene as described elsewhere
and partly here.

J-2 isn't a bad choice, nor is LOX/LH2 for the upper stage,
but clarification would have been nice.

That's my error,not his. We were doing quite a bit of different
possibility discussions and I'm not sure how I got that mixed up. His
notional case used a J2--yes, LOX/H2, and there was another one he had
analyzed that was ker/Lox. I got mixed up somewhere in there & didn't
look up which was which.