I don’t think it matters how rigorous the school is so much as how much you take advantage of it! A 98% would definitely help your chances, as would a varsity captainship! I think you can really make up for anything lost in an essay about being first gen, as well as positive recommendations. I read that (at least at Amherst, although they say it applies everywhere, I think it sounds right given UPenn’s culture) readers tend to look more favorably on applications that excite them, even if the stats aren’t there. So, if you seem like a genuinely interesting person, you can get away with a much much lower SAT score.