Thanks for you comments Henry. I should have added that the wood was kiln dried to 4%. It was sawed on a wood miser and is pretty close to exactly 3/4" thick. I understand about the softness of pine. I live in a rustic home in northern WI and think the softwood floor will fit in better than hardwood. My wife and I both like the worn look of softwood and neither of us has a problem with cracks between the boards in the winter when it shrinks.
The biggest problem I'm trying to solve is how to join the boards. I'm trying to stay away from tongue and groove. ($$$) I'm trying to decide weather to edge butt or try something else like ship lap. My wife also likes the look of face nailing with rectangular nails. I'm a little concerned that edge butting will leave too big a crack in the winter and ship lap may end up with cracked edges.