Fitting more bars in a line

[Keith Dunsire]

I am attempting to transpose a victoria piece from CPDL which is written in
Lilypond (http://www.upv.es/coro/victoria/ly/Vadam_Et_Circuibo_Civitatem.ly) the
PDf is http://www.upv.es/coro/victoria/pdf/Vadam_Et_Circuibo_Civitatem.pdf. 

I am using 2.11.something and have had to mess around with the Ly file to get it
to print. However I can't get it to print as compactly (7 a4 pages) as the
original PDF, as whatever I do I can't fit enough bars on a line.

I have used {fontSize = #-6
        \override StaffSymbol #'staff-space = #(magstep -6)} but that makes the 
notes
and text smaller but the bar width stays the same.

Please can anyone suggest what I can do to fit 8 or 9 bars per line rather than
7 or 8.

Thanks

Keith