Our purpose here is to run through a process that will produce a standard formatted epub with the minimum of effort.
And probably the easiest way to generate an epub document from those those text files is to use pandoc.
By using this combination, you get many powerful aspects of publishing to an epub file built into the tools and their defaults.
In order to have a properly formed epub document, you will need to include some information such as the author, title, licence, etc. This appears in the frontmatter and metadata of the document. If you are using pandoc, you can read up on it at http://pandoc.org/README#epub-metadata
One of the questions around the interface between old and new technology is that of page numbers. Should an ebook need to have page numbers? Why? This is a matter of debate For academic purposes, a mechanism to point to the source of an idea or quotation is important, and so I would suggest that some kind of reference system is needed.
In the case of paper books that is the page number and the way in which you can get a page number into your epub has been set out in the guidelines: http://www.idpf.org/accessibility/guidelines/content/xhtml/pagenum.php