WOW! I would think an interior design firm that does work for clients such as restaurants, clothing stores, etc. would be in the market or have a client in mind. TGI Fridays and others are decorated in such a manner but your signs are much larger than they use. We have a restaurant close that is an old railroad building and it is called the Freighthouse. It has some absolutely huge railway signs in their interior because they have the wall space and atmosphere to display them.
I would think another venue would be an auction house that deals with country store advertising. If you are close to a metropolitan area, a market should be available. If you have to ship these,freight would be the only way to do it and you would have to have them crated for protection.