I think I would center the TV in the center of the rock chimney. IF you MUST put your TV over the fireplace, it will always look off-center. I think artwork over your fireplace and another place for your TV. (Not so high, by the way)

Although Im not a fan of tv’s on the mantle I kind of like your arrangement of the 2 big black boxes. is the smaller box to the right of the tv necessary?

The inspiration of the shelving is good but maybe put something there with more visual weight—- the shelves seem a bit airy in comparison to the mantle and stone.