My system (i5-6600 and a RX480) gets around 80FPS average with occasional stuttering due to CPU issues.
I do not believe an i3 (unless heavily OC'd) would provide a good experience. AMD has a new series of CPUs that are rumored to be a significant improvement in the budget CPU area that will be out in March. If you do not want to wait, I would try and go for at least a i5-6400 with a Z series motherboard to BLCK OC.
As for GPU, I would go for a 6Gb 1060, 4Gb RX 470, or an 8Gb RX 480. 3Gb of VRAM (along with the cut cores of the 3Gb version of the 1060) will not be enough to run the game smoothly maxed out.