Thank you, I'm so happy to have finally done them!
I rescanned them as .TIFF files at 600 DPI, then lightened them from page-grain to white.
Then I added a transparent layer matching the green.
I flattened the image, saved to Greyscale and then lightened the grey all the way up to white.
I darkened the blacks and saved them as .JPGs.
I always thought it would work, but my old scans weren't good enough resolution. Now I want to rescan everything at 600 DPI.....! (no, it's not happening)
Really chuffed as these will now make the cut for the Rising Sun collected editions.