Sorry. Yes, the decorating forum has a lot about over-fireplace mounts, and it's generally not a good solution. The subject has been discussed before, so use the search button at the bottom of the page (the one on top doesn't work the same way.) Good luck. I saw a mount like that and it looked like a lot more work than it was worth.

Looking at these pictures, I also used the Dynamic mount for my Samsung 65". But the WAF plummeted because it hid the fireplace, so back to Costco and exchange for a 60". See attached pic. I'm very happy with the installation and ease of use. In the "up" position, it looks like a normal above-the-fireplace mount.

I would consider an "L" arrangement of the room so that you could either face the TV or the fireplace. If not, a corner fireplace is another option, which is what I have in my family room. But in that case, your current fireplace will probably not work unless you make a triangle shaped top for it. But they aren't that expensive so I would just sell that one, in that case, and buy a corner electric fireplace. I know they make them because I have shopped for one recently for a bedroom space. Another option is to put shelving units on either side of the fireplace and put the TV on one side. I have that arrangement in one of my guest bedrooms, albeit the shelving units are on either side of a dresser, but it still works. This won't work too well if the TV is huge.

It's easy to approximately figure out how much space you will be left with, but 1st you need to know the height of the fireplace heart which can be from 0-12" depends how high you want it to be... what size fireplace are you getting, the height of it... and you have to account for code-compliant clearance above + the combustibles you plan to have, i.e trim, wood surround, shelf or mantel, etc Known all the factors you will know the remaining wall height you left with and you can plan what size of TV you can put up there. Good luck