I have enough 604Es to do the 5 channel surround, in fact I have 7 so I can have two per side for each surround channel.

Eventually I'll get to hear it.

Probably construct 620 style enclosures, including a special mid one that provides a stand for a TV and has an angled baffle to point the horn up a few degrees.

Or I'll end up with a projector and use a perforated screen.