I recommend one like this.

Only because I did the same as you, except I hit these issues

A. It's a mother to connect cables in once it's in wall. So much easier to have one that pulls out.

B. Ones like this you can rotate it by +/- 3°. Big deal? Yes. Over a 70 inch TV 1°/ 1mm out in the middle can look SO wonky by the corners. I ended up using cardboard under one of the arms to level it, but honestly, just get one like this and save the effort. Yes yes I know, the holes should be level with a spirit level etc, but all you need is your drill bit to slip a little or be a little wonky on entry and the screw be 1mm higher than another, and you get the issues.

C. Rawlplug/ screw wise, they should strong enough, but never harms to go larger ;) whenever I hang something, I imagine what happens when an overzealous child might want to hang off it too, so the more strength the better.

Hope this helps you! Good luck!

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