Jay,
I am a woodworker, have had several tree's milled for my own use and can usually recognize a good tree when I find it. We own some farm land in Northwest Illinois. On that we have a small section of woods and within that is a spectacular black walnut. It has grown in an old woods, on high ground, so probably very slowly. I am pretty sure this would be a veneer quality log. Are you aware of any veneer mills or brokers?