Well there’s a lot to consider here. I do agree, the room is too small. I would not want to be in the front row 5’-9” away from an 85” screen and the LCR even closer. They’ll get blasted out of their seats while the ones in back will be struggling to hear. Dialog especially. You lose 6db per doubling of distance. Also, with the MLP in the center of the room, the bass response will be a black hole. The front and back rows will be extra bass heavy.
To me, this is also a two row room. But if you’re set on 9 then do what you can do.
For top speakers, this might be a case to run 7.x.6. Processors for that layout are expensive however, and some soundtracks have playback issues.
For surrounds, I’d considering doing arrays like in a commercial theater. Problem there is that the room is very narrow, and listeners in the far left and right seats will suffer hotspotting from too close proximity. That can be alleviated by using bipoles as surrounds. Dolby recommends using monopoles, and while I agree with that, bipoles can be pretty good there, but multiple rows could could be problematic. Are the surrounds going to be in wall? Because 17” from the couch to the wall is not enough room for a speaker, and will be extremely annoying, and not immersive.
The ceiling is also a little low for Atmos in a single row setup, and even more so here.
Iirc after all that, lol, the question was about the Top/height speakers.
I would install them at the recommended 45° fore and aft of the MLP and let the front and back rows get what they get. That way at least one seat, the most important one will potentially get good playback. Also, with that ceiling height I would not space the as wide as the mains. I would keep their width at the .5 to .7 of the widest speakers width(usually surrounds).
This is a case of 10 gallons of water in a 5 gallon bucket.