I say look at some older klipsch Heritage speakers like the Lascalas or cornwalls, or Chorus. These are all around 100db efficient and work great in a big room. I have the Klipsch Epics Cf3's. They are 100 dB efficient and they can crank with uncompressed sound that can easily fill a large room. I can only imagine a room with those all around, it would be awesome. Their size and looks are perfect for a big space like that as well. Or look for some speakers that are used in a movie theater. I also vote for a front projection system of some kind. Mine is a 90" diagonal but will soon go up to a 106" when I get my new projector.
That room will be alot of fun to create. Best of Luck for your friend.
That room will be alot of fun to create. Best of Luck for your friend.