Thanks for the drawings. Lots of planning to be done. Am I right in concluding the top of the midrange box is flat and the elevation is a perspective of some sort? I think I can make this work after preliminary discussions with my very tolerant wife. (Her suggestion was to mount them upside down at ceiling level - probably won't happen!
The good news is that the Thiels are already huge and sit out in the room taking up space - even the not-insignificant sevens will be less obtrusive.
I'll scan the forum for construction tips and pictures.
tim