\ifcase \@ptsize\relax 

\voffset= -30pt
\textheight 580pt 	% increase from 536pt
\textwidth  450pt	% increase from 360pt
\hoffset= -45pt		% compensate to keep centered
\if@twoside 
	\reversemarginpar	% I assume the binding side is the
	\oddsidemargin 70pt 	% bigger margin, so reverse the
	\evensidemargin 38pt 	% placement  of marginpars
	\marginparwidth 40pt	% less of a margin to work with
  \else \oddsidemargin 54pt \evensidemargin 54pt \marginparwidth 83pt 
	\fi

\or	% 11pt

\voffset= -30pt
\textheight 580pt 	% increase from 536pt
\textwidth  450pt	% increase from 360pt
\hoffset= -45pt		% compensate to keep centered
\if@twoside 
	\reversemarginpar	% I assume the binding side is the
	\oddsidemargin 70pt 	% bigger margin, so reverse the
	\evensidemargin 38pt 	% placement  of marginpars
	\marginparwidth 40pt	% less of a margin to work with
  \else \oddsidemargin 54pt \evensidemargin 54pt \marginparwidth 83pt 
	\fi

\or	% 12pt

\voffset= -30pt
\textheight 580pt 	% increase from 536pt
\textwidth  450pt	% increase from 360pt
\hoffset= -45pt		% compensate to keep centered
\if@twoside 
	\reversemarginpar	% I assume the binding side is the
	\oddsidemargin 70pt 	% bigger margin, so reverse the
	\evensidemargin 38pt 	% placement  of marginpars
	\marginparwidth 40pt	% less of a margin to work with
  \else \oddsidemargin 54pt \evensidemargin 54pt \marginparwidth 83pt 
	\fi

\fi