A 3.7 c/sGPA and re-take 512 should land you an MD somewhere if you've kept up with your ECs (this being a huge factor, not sure how much you did when you knew you were already guaranteed a seat in medical school). If all you have is grades and MCAT you would probably need to take at least one more gap year to boost the rest of your application. If you're gunning for surgical subspecialties, Derm, Rads etc. it might be worth doing.