Honestly I would suggest to get a 9 or 11 channel Atmos receiver, and use 4 of the ceiling speakers for front and rear height channels. Then add ether 5 or 7 speakers for front and surround channels. I have Atmos in my basement theatre with ceiling speakers and it is amazingly enveloping. I also have Atmos in my living room with reflecting(up-firing) speakers and that works ok as well. Another option is to use the back pair as surround speakers, and the front pair as front height (without using any rear height channel). You'll need to add a pair of speakers and centre speaker for the front channels. You don't really want dialog coming from the ceiling. High mounted surround channels can work well though.