When I had my Bv 7-40 Mk3,my projection screen came down infront of the tv and stopped just above the 7-1 speaker,which was no problem and it does the same now with the 7-55 and Bl 10 but in your case maybe a set of Bl 4000 if you could mount them above the screen some how.
Mine did have the Ast in the menu but could not use it.
I loved my Bv 7-40 Mk3 was a great set but moved on up..lol.
I think the Mk3 is a good used choice.
Bv7-55 & Bv7-32...Blue,lab1's x4,Yes4Blue, 6000x4Blue,Beocom6000 Blue,Beo5.Oh what a Blue set-up & a Beosound 5...After all,its Bang&Olufsen!