I see, my concern is exactly as PA stated... The Wooly Adeldgid. You may not have them ever or not until several years down the road but if you do treating that many Hemlocks can be expensive. I would look at the wooded area around your place and see what evergreens are most common and are in good health. That way you know what likes that soil and micro climate. If Hemlocks seem to be the most common you may still want want consider another option like White pine, which is native to the area and grows relatively fast along with being pretty insect and disease resistant. Norway spruce may be another choice but it's not native and I have seen them with needlecast (a common disease). Let us know what grows good naturally there and we can help ya out some more.