I want to share another excellent resource for modernized Christian classic books: http://www.onthewing.org/Classics.html. These resources are provided free by On the Wing. William Gross has done an extensive amount of work modernizing many classics from Bunyan to Owen.
These books have updated language and use modern formatting to assist with understanding. They also make use of footnotes with additional scripture references. You can download them as PDFs or eBooks.
Having worked on these for many years, this library of updated works is extensive and worth checking out.