and yes, i think G4560 will bottleneck 480, but with $20 canadian difference, its worth it. The bottleneck will only occur on heavy cpu games such as Battlefield1 that has been called i5 killer. BF1 actually demand 6 thread to operate normally without any tweaking thus cpu with 4 thread will have trouble.
BUT
really $20 Canadian for upgrade from 470 to 480. Its just crazy to pass.
And the G4560 (its actually an i3) will have no trouble in less cpu demanding game.
Not to mention, the recommendation I gave above is actually cheaper than the OP initial build but with RX 480. so nothing to lose here.