The Zeph fonts are based on 'Porson' Greek according to the information provided by Harvard University Press. But the Zeph* fonts themselves seem to be custom commissions for HUP for use in Loeb books. So I doubt you will find anything to give you identical results. If others have found the fonts attractive, you might find something inspired by them but I suspect that's going to be the closest you'll get.
For Greek, the Greek Font Society (GFS) provides a font based on 'Porson' which might be your best bet. The Greek Font Foundry offers an alternative.
GFS Porson is fully supported for use with TeX. A package is available from CTAN which provides both fonts and LaTeX support. The package is included in both MiKTeX and TeX Live as gfsporson
. Reading the documentation, you might try something like this:
\documentclass[greek,british]{article}
\usepackage{babel}
\usepackage{gfsdidot,texnames}
\usepackage{gfsporson}
\newcommand{\greek}[1]{\foreignlanguage{greek}{\textporson{#1}}}
\begin{document}
The heights of the letters in the \LaTeX{} package supporting GFS Porson are adjusted to match the Latin fonts from GFS Didot.
Latin and \greek{dokim'h}.
\end{document}

I've used GFS Didot for Latin since the heights of Porson's Greek are set up to match the Latin script from Didot but obviously you could match Porson with a different Latin script if preferred. Like gfsporson
, gfsdidot
is available from CTAN and included in both MiKTeX and TeX Live.
gfsporson
might be your best bet for Greek since that's also based on 'Porson'. There is also web.archive.org/web/20071028001414/http://www.geocities.com/…. – cfr Mar 2 '14 at 16:26