Do a search of this forum for PDFRead -- this allows the conversion from PDF (including graphics) to any of several different ereader formats. Be sure to select PRS500.
It works excellently for the GoogleBooks files which are nothing but graphic images of the original pages of the books, and which don't show on the reader at all except for the initial Google page.
I'm thinking that you might end up with a file that includes everything. It's worth a try.