I meant you can scan at 300 dpi, import them into Scan Tailor, and Scan Tailor outputs 600 dpi (by default). Don't worry about "adding in pixels that are not there". Pages will look just fine because the antialiasing that I was telling you about, is done "on-the-fly" by the e-reader trying to display it on a smaller scale.
Can you guess which one compresses better?
Again, do not resample what you get from Scan Tailor using Acrobat. The 600 dpi images you get from Scan Tailor are just fine, as long they're 1 bit images (black and white), with none of that gradient stuff when you zoom in.