If you are so inclined, please post a representative file with the two pictures and the imperfection. This will give us a better idea as to the problem.
Using the Rectangular marquee tool, I made a selection of a "good" area next to the text, and placed that on its own layer (CTRL+J). Then, with the move tool, nudged it over the distraction as a patch.
For some of the other areas, I opened a blank layer at the top, filled it with 50%gray & overlay blending mode.
Used the eyedropper tool to sample adjacent color and painted over defects with the brush tool @40% opacity.
Another option for your purpose may be to scan the pages individually and place them on a new background. You would have 100% control of the size to make it conform to the size of your paper stock.
thanks, all good suggestions. The two sides are different scans and on different layers right now. I will try your ideas and report back.