[Pablo]

My usual workflow:

1. Crop with Briss to do away with headers and footers, if necessary.
2. Convert with Mobipocket Creator.
3. Load the HTML with Sigil.
4. Edit during endless hours.

In willus' page you can find links to the Briss download page. Mobipocket Creator site is down for ever, but I suppose you can get the installer somewhere else if you look hard enough.

I have yet to try loading a pdf with Word and see how it converts, as willus suggests.

Problems normally found when converting pdf files:

1. Broken paragraphs, specially at page breaks.
2. Lost scene changes.
3. Lost formatting: italics, bold, font size changes.

Good luck!