I have had quite good and readable results with this and that's why I posted it. Sometimes, a little cleaning for the headers of the book is requested because they may have a slightly different formatting than the rest of the text. But Gutenberg's are OK for my experience.
Well, just try it and let me know if we can improve something. It's free.
Let me give you an easy example here so that you can check the results by yourself: I uploaded here the shortest book from Gutenberg Australia I could find (Collected stories 23 k) and the output using the recommended method above. (Cleaned collected stories 68k) as a rtf file.
First step : 444 occurences removed
Second step : 149 occurences added (paragraph breaks)
After that I inserted in my 9x12 cm model and saved as a rtf file.
Please note that for the first step, I changed $ with a space.
To finish with it, you can make a macro with these two steps (choose Tool Register macro) and it's quite handy and quick.