I think the blocks were 8" finished and about 11" diagonally. If you get a lot of sun, be sure to interline them with something heavy so they are opaque.
I'm not sure exactly how big the room is - it is BIG. We live in an old Victorian farmhouse. It used to be the parsonage for the Episcopal church next door, and now they rent it to us. :-) When we first moved from the farm to town, I was very unhappy, but I just love this house. I hope we can stay here along time.
I will ask DH for his tape measure when he gets home.