Good luck on this one: I’m in Annapolis, I can’t get people to ‘harvest’ large trees (maple, Oak) coming from my property – we’ve had several downed trees from storms over the years; as well as trees which have simply died for one reason or another.
The mills are telling me the cost to take them down, transport, process, … make it un-economical. With the cost of Walnut, about $11/bf (if my memory is correct), the economics might shift in your favor.
The hard question is drying-time: I think it’s about a year/inch thickness – though, I’ve never seriously looked into this.
Please keep us posted on your progress: I hope you find a local wood mill that can help you on this.