I am planning to setup a surround sound system with in-ceiling speakers at the back, one to the left and one to the right. I already have the pre-wiring to mount the in-ceiling speakers at the back.

I have an older Panasonic TC P50ST30 (release review/specs here) that was generously given to be by another Arsian that does have ARC support (I think). The TV sitting in front of an old but nicer ...