\documentclass[12pt,landscape,twoside]{book}
\usepackage{gcheck}

\usepackage[portrait]{geometry}
\geometry{landscape=false, includemp, margin=1cm, 
          bindingoffset=1cm, heightrounded} 
\geometry{marginparwidth=3cm, includehead}
\geometry{dvipdfm=false}
\geometry{mag=1414, truedimen}
\geometry{showframe}

\begin{document}

\typeout{}
\dcheck\paperwidth{614.28824pt}
\dcheck\paperheight{794.96506pt}
\dcheck\textwidth{256.72127pt}
\dcheck\textheight{476.0pt}
\dcheck\oddsidemargin{5.79622pt}
\dcheck\evensidemargin{69.70174pt}
\dcheck\topmargin{-22.65652pt}
\dcheck\headheight{12pt}
\dcheck\headsep{19.8738pt}
\dcheck\footskip{30pt}
\dcheck\marginparwidth{85.35826pt}
\dcheck\marginparsep{7pt}
\dcheck\columnsep{10pt}
\dcheck\hoffset{0pt}
\dcheck\voffset{0pt}
\ccheck\mag{1414}
\checkresults
\typeout{}

\manyfoxes\manyfoxes\manyfoxes\manyfoxes
\manyfoxes\manyfoxes\manyfoxes\manyfoxes
\end{document}
