Sorry I thought this thread had ended. You might try this link to the help files using "ebook-convert" This is a command line command(program). It uses "switches" like "--title or "--authors" so that you can change the way Calibre converts your file. Just glancing hastily at it I saw switches to allow you to change fonts in several input formats. Just look for the input file you want to convert from to LRF and follow that link and the instructions.
here's the link:
http://calibre-ebook.com/user_manual...k-convert.html
HTH
Paul