Has your S decided what to do with regard to testing? I am in the group who would have him retake ACT or SAT before taking subject tests, if he decides to take any at all. If he does retake tests, adequate preparation would be good. Subject tests can be difficult and some don’t directly mirror the content from a given HS class…like lit, which is difficult analytically and poetry heavy. At the schools on your S’s list Math 2 would be strongly preferred over Math 1…I would not send a 710 Math 1 score to any of the top schools on his list.
With that said, I would probably have him not retake any tests, but rather focus on apps and getting good first semester grades. Good luck.