How hard is it to transfer to University of North Carolina at Chapel Hill as a junior?

I just graduated from high school and will be entering as a freshman at University of Oregon this fall. However, U of O has never been my first choice! I really interested in transferring to UNC as a junior. I was just wondering if the college GPA is much more focused on my ACT scores? MY high school GPA is 3.8-3.9 uw, couldn't remember exactly! However, my ACt score is like 22, I know it sucks! But I cotinue to work hard and get 3.8-4.0 at U of O, what's my chance? Not to mention I will join in clubs and various activities!