This is someone's take on an English overmantel. Have a mirror company come and do a template and fill that space with a mirror that is custom fitted to the space. The sconces are all wrong. They're way too small and they're put ridiculously low. Get the mirror first and then see what works for sconces and hand them significantly higher.

My goodness, is that really a live fish? I would for one thing move it away from the fireplace and give it a much larger space, preferably not in the living room. An area rug over your carpet, perhaps tying in with the teal colors of your pillows, if you decide to go in that direction, would also give more life and color to your room. Try esalerugs for transitional rugs in polypropylene which are easy to care for an can even be hosed off outside when they get dirty.

When decorating your mantel think of the rule of threes. For instance a lovely landscape painting with a candlestick or vase on either side. A nice antique oak mantel clock would fill the bill for rustic. Or a framed old map of your region. Check local or regional artist who work in wrought iron. They may be able to make a fireplace screen for you.

Waht part are you planning for the mantel? Please at least lower the art work on the adjacement wall better yet get some art with some color. It hink you need to get some graph paper and draw different lenths of mantel to scale on that wall IMO a large piece of art above the fire box . Mayeb show us exactly where the 60" will go . This ois a pic of a FP similar to yours for a visual