I suggest you get legal counselling before doing that.
It is entirely possible that, in some countries and possibly in the US, a not exercised copyright allows under certain circumstances any entity to copy a book (provided other rights of the author, such as paternity and work integrity, are respected). Even if such a norm exists in the US, you should check if there is, as there would probably be, a procedure that you have to observe in order to be able to copy the work: for instance, notifying the copyright holder of your intention to publish the book, if they don't. There might be some terms for your warning and the copyright holder's publication. Those terms expired you might be able to copy the work.
Just like in different cases of intellectual property such as patents and trademarks, also in the case of copyright it is quite conceivable that the ratio of the law is not only to protect the right of the author to see its authorship recognised (paternity right), to see the work to be distributed entirely (right of integrity of work), and the obvious right to enjoy the profits of the copying (patrimonial rights on the work), but also to protect and foster the right of the general public to know the work, and the right of the author to see his work diffused. If the copyright holder does not exercise its right to print the work, he deprives society of the work itself and deprives the author, if different from the copyright holder, of an important part of his rights.
Imagine, to make a school case, somebody buying the right to a book only for jealousy, and then not publishing it because it would obfuscate the merits of his own book. Imagine a rich Ben Jonson, in modern times, buying the rights to Shakespeare plays to eliminate them from the scene... or just imagine, in modern times, Shakespeare's publisher to run out of money and not publish anything, hoping he might be able to publish them one day, in the future.
So, in general, it is quite possible, or even quite likely, that the patrimonial rights of copy come, in the hidden plies of the laws, with some implicit strings to actually exercise the copyright, or lose it.
In Italy IIRC and no, I'm not going to scavenge laws, it is not considered a copyright violation an integral photocopy for study purposes of a book which is out of print. That is different from a new edition though, as each student, who is in need of studying the book, has the right to make one photocopy only, his personal photocopy of the book.
So it might be that if the copyright holder does not exercise his copyright, somebody else has the right to do it, but there probably is a procedure, and the entire process is full of risks if you chose the DIY route.
There certainly might be a legal way to do that, but by every means do it legally get professional advice.
PS And I do take you very seriously. Works must be published. If they are not, I do sympathise with any effort to bring them back to life, in the author's interest, and in the interest of society at large.
PS I think for books the patrimonial copy rights expire after 70 years after the death of the author. Non-patrimonial rights, such as right to paternity and right to integrity of the work, obviously never expire.