If you think you can bring that Science score up, then go for it. I know Science is my worst section too

I talked to an admissions officer and he specifically stated that Penn does *not* have a preference between the SAT and ACT. All they want to see is a good score. I think you're competitive for ED, but a higher score can only help you, right? They can see your specific subscores, and my understanding is that they superscore your subscores but I am not positive on that. Good luck!
Chance a junior for Top 20 (will chance back)