"tou" ? you meant "dou" ? to ask advice?
I think you leveled too much the page, leveling is really useful because it does half of the job on editing scans, but if overused it looks just as bad

here are the tools I'm using for editing jump scans:
- leveling to adjust rapidly the black and white
- my tablet + polygonal lasso to remove the dust on the white & filling the black parts
- copy/paste dodge&burn and clone stamp to rebuild the tones
- brush tool to redraw parts of the drawing under some text.
note that working with the digital pen of tablet instead of the mouse is making things easier (as long as you know how to handle that pen, because it's not really easy at first)
I could do a tutorial to show more clearly how I do, but that looks so loooong to do...