@Jellby
http://ebooks.adelaide.edu.au have a copy, but the images might be from the gutenberg edition. No chapter head decorations either. Quality maybe a very tiny bit better than what you have.
Re: turning up the chroma --- does GIMP have a tool for dodge and burn? Sometimes dodge can bring out details that were hidden in the dark shadows. In PSP I use a dodge brush on small areas to do that, rather than brightening and lightening the entire image. (or vice-versa, use burn brush on small areas to make details darker).