Nick, you could have him get inwall M2's for the surrounds. I know they're not as good, but they're not as expensive, either. And if he's still in the framing stage, you could place them optimally. Less $ and higher WAF. Just sayin'.
I think that there are some architectural issues to overcome. It won't be a dedicated space, so the surrounds will most likely need to be mounted using ceiling mounts vs. on the wall.
I will know more tomorrow when we get into the space with tape measures and such, but good idea on the M2 in-walls.
M60s, VP180, VP150, QS8s, M3s, SVS 20-39PCi, Shakers