Why not open it with the caveat that you'll open something else if the wine sucks? Then taste it and tell us about it? If it sucks, the kosher forum is probably a good place to announce it. If it doesn't, you can discuss its glory here. Either way, how is it not worthwhile to open and taste a bottle? Especially if you think it might be a piece of history. Let me tell you, there are still not enough vintages of potentially good kosher wine out there that it could not be considered a piece of history.