Here are wall or ceiling mount speakers from Yorkville Sound. These model WM5T/70 speakers are passive 2 way speakers that are set up for 8 ohm operation or even 4 ohm. These can be part of a 70v system with the addition of a matching transformer which is easy to get. There is a 5" low frequency driver and a mylar dome tweeter. The overall  dimensions are 8.5" x 12" and the cutout or hole size is 7.5" x 11". The depth of the speaker is 2.5".
The pictures will show off the speaker well so please check them out. 
These were installed in a library and were gently used.