It really depends on my major, like I'm applying to engineering or math and I have 800 math II 800 US 780 Chem... I think you should definitely aim for 750+ in any SAT II (because they are supposedly easier than SATs, but I disagree) if you are an unhooked applicant. Or at the minimum 700+ in an unrelated subject. You should strive for 1 math, 1 science, 1 humanities, minus 1 of those if you need though. Some schools have requirements and for any ivy league 750+ is pretty standard, but 700+ is sufficient tbh. Upper 600s isn't great.
Then again, as long as they are above 700 (or 650 if unrelated) it won't hurt, but if you are unhooked you should probably try to fix any loose end to your application.