[PeterT]

If you look at the original version; it uses TTF font's; not OTF. Also, the fonts are placed at the base level of the ePub file; not in a sub directory.

So the urls in the CSS are of the form

src: url(Times-New-Roman-400-Italic-7c7c6c12-7019-4025-8edf-1d05c9eb7dbd.ttf)

and not

src: url(../Fonts/Times-New-Roman-400-Italic-7c7c6c12-7019-4025-8edf-1d05c9eb7dbd.otf)

It looks like http://typeface.neocracy.org/fonts.html has the ability to convert from OTF to TTF