Submitting an ACT, an SAT 1 result and a single SAT subject test seems to cover a breadth of testing that most colleges would be happy to see (and which would seem to be at least the equivalent of an SAT 1 exam combined with two Subject Tests, but no ACT). If your son might test further, I’d suggest a retake of the ACT, at least if he feels he may have performed below his potential with the 32.