It has been a while since I went to the Arkansas History Commission but they had either the document microfilmed or a copy of the book, I can't remember which, but they did have it in some form. Now if it is housed in a public archives, I would think that makes it in the public arena and a reprint of the diary with new editing and footnotes would be legal and fine. Of course "I ain't nary a lawyer" but being in a state facility, open to public research etc, I would think it safe to reprint and edit as a new publication. Just my two cents (Confederate) worth.

Anthony