Welcome to the forum and dont cut to many of those trees down because I need some for my house when my wife and I move back!
I have cut about 5000 bf of spruce in the last few years and I keep everything that is 8" diameter or larger. they make great 2x4 and 2x6 material.
If you making 3 sided cants for the log on log walls I think you will be surprised how well those 10" logs work out. You may consider those with the smaller tops that wont give you the 8" flat your looking for you can shorten the log to 8 foot, assuming supply of logs is available on the property your talking about.
If not, depending on your location in the Great State of Alaska, your entitled to 10,000 BF of Timber for personal use for FREE!
I know when my wife and I were in Haines looking for property that program was primarily available in the entire southeast portion of the state.
We have since changed plans a bit and are looking to move to the Kenai Peninsula area and the timber program is not available in that area.