Man of Honour
Only put it above the mantlepiece if you have a corner sofa
it looks like there's a fireplace in the way of your av/sound system. if you weren't gonna use the fire why not just put the tv in front of the fireplace
TV only goes above the mantelpiece if you're going to be watching The Chase nonstop
Looking good.
A tip from me, lay your L&R speakers down on their side, it will not only look more cohesive but should sound a bit better as the drivers/tweeters will all be on the same plane.
I'm going through the same dilemma at the moment so it's helpful to see it mounted.
My mantle is around the same height but far wider, and looks horrific, so I'm thinking about either ripping it out and getting a more modern mantle installed or building a fake TV wall around it.