Welcome back Q-Man. I went Atmos 7.2.4 myself in the basement HT mancave. My budget is pretty sensitive so I got a lot of bang-for-the-buck from used Klipsch Pro speakers, 2 KPT-110s for side surrounds, 2 KP-102s for back surrounds, and 4 KI-102s for ceiling Atmos. I mounted the ceiling speakers to an "X" made of 2x4s bolted to the joists in 2 places along which they can slide for experimentation with placement angles. Just getting it running this week.
New processor is a used Anthem AVM60 (my 2nd one- also have one in the living room) bought through a local dealer who gave a 1 year warranty.