I have a few thoughts (my thoughts, not legal advice) when it comes to old documents, copyright and Archive.org. I think that the bigger issues that annoy copyright holders are a) people who claim that the material is their own, and b) people who are selling and making a profit from the material (and I don't count those websites that found them for free on the internet and are reselling them, although they do provide a convenience).
I believe that the main purpose of Archive.org is to preserve the world's digital media before it disappears and is lost forever. I have even read about them going to court and defending their ability to do this, as well as acting like any other library that has copyrighted material available for loan.
I also wonder if the material (or product it relates to) is currently available for sale or still supported by the copyright holder and does the material or product still have commercial value (not counting used sales). The usual answers (with only a few exceptions) are No. And why would a copyright holder spend the money to pursue infringement for an item that is no longer commercially viable for them. One scenario would be to reduce use of the old obsolete product in the belief that it would promote sales of a newer replacement product. This move could be risky and often lead to negative PR and reduced sales of a newer product. Why would a customer buy a new product from a company where it would be expected that they will actively suppress your ability to use and enjoy their product after their definition of its lifespan.
In summary, my concern for preserving (and making available) old documents, usually outweighs any concern for any copyright infringement action. In addition, it could be harder for a copyright holder to bring a successful infringement action unless they first politely asked you to remove or take down said material first.
