BookCreator (BC) is ideal for converting text to "Your format". I initially wrote the tool because I was dong a log of converting ProjectGutenberg text to LRF. Text is the best format for BC because it has no hidden metadata like HTML.
BC is just a gloried word template that adds menus, styles, and macros to MS word all targeted toward making the eBook creation easy. Some add features like title formating, word warp fixes, auto chapter detection, text-italic (this requires the _word_ text convention.), table of conent creator, etc...
The nice thing about the tool is it is built within MS Word so you get the rich editing experience MS Word provides with macros to help create an ebook. And the bad thing is you need MS Word
The tool uses calibre to make 7 different book types, LRF is one of them.