Centering Systems

[josh]

Hello.

A while back, someone was kind enough to provide me with the following 
code to center systems on pages

#(define-markup-list-command (center-column-list-args layout props args)
  (markup-list?)
  #:properties ((baseline-skip))
  (let ((stils (interpret-markup-list layout props args))
        (line-width (ly:output-def-lookup layout 'line-width)))
  (space-lines baseline-skip
    (map
      (lambda (arg)
        (ly:stencil-translate-axis
          arg
          (/ (- line-width (interval-length (ly:stencil-extent arg X))) 2)
          X))
      stils))))

I then wrap the score block and call it with this:

\markuplist \center-column-list-args \score-lines { \theScore }

It worked great. I use it for a very specific circumstance for some of 
the music I engrave. Since that time, I have moved to using ANSI C paper 
size (11" x 17") and now the systems do not fill to the bottom of the 
page. The problem is, I have never gotten the hang of scripts and I 
don't quite know what I am looking at. Which values in the script should 
I update to allow the systems to vertically fill the new page size?

Many thanks in advance.