I'm not much help on this, sorry. But I will just say that in general the vast majority of trees prefer full sun and no competition from other trees. I would imagine that the Green Giants and Norway Spruces would do fine in this situation, but it would be a stretch to ask them to be as full or vigorous as ones that are grown in full sun by themselves. I say go for it.

I don't live in the Eastern US, but there are some plants that do well in such a wooded setting, like American Holly.