The woods port is gonna give you UNBELIEVABLE midrange power. Personally, I think you should try a 15 or 16 and see how you like it. If you dont like it, then you can always change. Sprockets are cheap.
When you say you want ur good botton end, but dont want to lose ur top, that's why I say run a bigger sprocket. Ur gonna have enough power to pull the bigger sprocket.