I think the way to do it is to notify her estate and let them pursue it or not. But I'm really just here to say how I'm happy to pay her estate and publishers and everyone else should too.
As another comment points out, Le Guin herself does not call this a translation, so we shouldn't misrepresent it (although it might be my favorite English version).
However, it's not in the public domain. Her work deserves all the attention it can get, but I'd rather not see it pirated wholesale.