A little ancient notation trouble

[Shane Brandes]

Hi Lilyponders,

   I am working on typesetting some very old hymns that were set in
mensural notation. The trouble is that when trying to replicate the
equal spacing (basically like letters out of a typewriter one right
after the next) one can set the score timing off, but then the systems
trails of the edge of the page.  So I am left with the option of using
length multipliers to cheat the length. e.g. c\longa*1/8 etc. Does
anyone know an easier way?

Shane