It has been a long day, so let me make a few brief comments.

There are stable 7.x.4 receivers, but they aren't cheap.

The $700 Atmos receiver is lacking some bells and whistles, but depending on his room size, a 5.1.2 setup could work just fine.

You did mention that there is no room for ceiling speakers, why is that?

M3s are still decent enough speakers depending on the room size.

Farewell - June 4, 2020