memoir
offers facilities which I think provide the information you want (p25 of the documentation).
\documentclass[12pt,twocolumn]{memoir}
\usepackage{lipsum}
\settypeoutlayoutunit{mm}% note: needs to come *first* to have any effect (documentation is wrong)
\typeoutlayout
\typeoutstandardlayout
\begin{document}
\lipsum
\end{document}
Then the output includes this information:
******************************************************
Stock height and width: 279.39671mm by 215.89746mm
Top and edge trims: 0mm and 0mm
Page height and width: 279.39671mm by 215.89746mm
Text height and width: 192.77344mm by 164.83272mm
Spine and edge margins: 20.47931mm and 30.58543mm
Upper and lower margins: 43.80676mm and 42.8165mm
Headheight and headsep: 5.0961mm and 6.98476mm
Footskip: 10.54367mm
Columnsep and columnseprule: 3.51456mm and 0mm
Marginparsep and marginparwidth: 3.51456mm and 16.86987mm
Sidecapsep and sidecapwidth: 3.51456mm and 16.86987mm
Sidebarhsep and sidebarwidth: 3.51456mm and 16.86987mm
Sidebarvsep and sidebartopsep: 5.0961mm and 0mm
Sidebarheight: 192.12323mm
Sidefoothsep and sidefootwidth: 3.51456mm and 16.86987mm
Sidefootvsep and sidefootheight: 5.0961mm and 192.12323mm
******************************************************
******************************************************
Page height and width: 279.39671mm by 215.89746mm
Text height and width: 192.77344mm by 164.83272mm
Oddside and evenside margins: -4.92038mm and 4.92038mm
Topmargin and footskip: 6.3262mm and 10.54367mm
Headheight and headsep: 5.0961mm and 6.98476mm
Columnsep and columnseprule: 3.51456mm and 0mm
Marginparsep and marginparwidth: 3.51456mm and 16.86987mm
******************************************************
So I think you want something like this:
\documentclass[12pt]{memoir}
\usepackage{lipsum}
\setlength{\textwidth}{164.83272mm}
\setlength{\marginparsep}{3.51456mm}
\setlength{\marginparwidth}{16.86987mm}
\setlength{\oddsidemargin}{-4.92038mm}
\setlength{\evensidemargin}{4.92038mm}
\settypeoutlayoutunit{mm}
\typeoutlayout
\typeoutstandardlayout
\begin{document}
\lipsum
\end{document}
In the image below the pages are reversed from normal positioning i.e. my viewer puts the odd pages on the left rather than the right - hence the odd spacing effect.

Note that this flies in the face of memoir
's raison d'être...
layout
is wrong, andlayouts
lacks relevant information.multicol
does), perhaps that's what I should aim for.geometry
?