Thanks. I like the added wood piece for the mount to hit the studs, smart. It does look similar to my 261. My hookups are actually not on that small wall but on the "outside" wall. I think you wrote that you added these, my unit already has the outlets but no mark for where to attach a mount.
I may dry fit and see if I can make it work on the small wall, so the TV can swivel in place and lock. I prefer that location. If it won't fit, I'll bolt it to the larger wall and swivel over.
Looks like you did a great job!