Set yourself up academically. Step 1 may be P/F for you but Step 1 sets a good foundation for Step 2. Medicine tends to be cumulative such that those who build a strong foundation academically early on tend to do better later on as well. Step 2 will be the primary determinant for competitive specialties in the years to come (in terms of comparing applicants anyway).
Get into research and networking with those departments as soon as you are able without sacrificing academics. Better to get started earlier so you should try to figure out which one of those specialties you're more into. Shadow surgeons and see what you're more interested in. Then do research in that specialty. Alternatively could do research in both specialties until you decide but you're halving your productivity. Network, network, network. Could not emphasize that enough for competitive specialties.