As I shared up thread, my son was able to use his eighth-grade physics score for every school to which he applied, including several Ivy Leagues, except for Caltech. It seems they have changed their policy, as I do not find anything about the necessity of using recent scores on their website today. I would imagine he could have used his eighth-grade math II score, as well, if he had not chosen to retake it in 10th grade.
I think we called schools to make sure it was OK.