If you can, use a "bellows" lens such as the Minolta Rokkor Bellows 100/f/4. It is a lens without focusing helicoid, especially optimized for bellows use and for this kind of work. Just like any other macro lens, it is optimized for short distance work. Unlike normal macro lenses though, those bellows lenses are optimized for planarity of field and border sharpness (or, if you prefer, sharpness uniformity between centre and corners) which makes them particularly suitable for reproduction works - documents, stamps - which is their reason to exist.
It might be that an enlarger lens is also quite apt to this kind of task.
If you use a Sony camera I think you can easily find adapters between Minolta AF and Minolta SR. Maybe the Rokkor bellows lens was also produced in Minolta AF mount. As you are making reproduction work I don't think you care about diaphragm automatism, especially if the camera you are using has magnified live-view function for focusing, so you can use any make through any adapter. You don't care about infinity focusing so any "reproduction" lens will be perfect. Again, I suggest looking into the enlarger lens field and their adaptability to this kind of work, for which I suspect they should be quite capable.
If your numeric camera has magnified live view I would use it for focusing, so that you can focus at the exact work aperture (if you focus at full aperture and then close the diaphragm a small focus shift can be produced, depending on the lens you use).
Best wishes for the work