I've been round this loop a couple of times over the last couple of years, trying to help users to read screenplays. The closest look & feel I could achieve was to
- open the PDF, highlight all the text and paste into a TXT file. Naturally this will lose any bold and italic formatting. See next post for update
- transfer the TXT file to the reader (i.e. no conversion) and read, preferably in landscape mode. It would look best if it could be read using the reader's monospace font
- if you have no option but to do a calibre conversion, then it needed to be a TXT to EPUB and use TXT input conversion options which preserve all whitespace and make no attempt to reflow lines into paragraphs, i.e. assume every line is a paragraph. I also specified body {font-family: monospace} in Look&Feel - ExtraCSS
This worked not
too badly with my WinXP/Sony reader setup.
What typically went wrong for Mac users was that they were not able to copy/paste in step 1 without losing all leading spaces - thereby losing any semblance of positional formating e.g. centered dialog. Not having any clue at all about Mac I was not able to offer any suggestions.
Also I have no idea whether a Kindle can directly read a raw TXT file or whether you would get a similar result if converting TXT to MOBI with the monospace option.
Maybe there's some ideas here you can try.