I would not find a problem, generally speaking, in using seasoned wood rather than green wood. I would count the ring density per inch as an indicator of strength, higher the count greater the strength and weight. Do you know where the timber was grown, Sitka spruce range from northern California to Alaska, more northern timber is heavier and stronger than southern timber, in general? Seasoned timber should require less offset if you are draw boring and will more likely conform to the shape it was cut.

It really boils down to cost, engineering requirement, suitability of the stock and available substitution. So the range of answers flows from perfect to crap. Really there is nothing to work with here to give any answers.