Measures width

[gio]

Hello everybody!!

there's a way for override the measures width?? I'm trying to prepare a
score with only the chord names, with four measures with the same width
in each row, something like this:

| C7      | F7      | C7      | G-7 C7  |
| F7      |         | C7  B7  | Bb7 A7  |
| D-7     | G7      | C7  A7  | D7  G7  |

This is the code I've used:


\new ChordNames 

  \with {
    \override BarLine #'bar-size = #4
    \consists Bar_engraver
    \consists "Volta_engraver"
  }

  { \override ChordName #'font-size = #2
    \chordmode {                                                       
    c1:7    f:7   c:7   g2:m7  c:7  \break
    f1:7    r     c2:7  b:7   bes:7  a:7  \break
    d1:m7   g:7   c2:7  a:7  d:7  g:7 \bar "|."
    } 
  }

\layout {
  indent = #0
  \context {
    \Score
    \remove "Bar_number_engraver"
  }
}


As you can see the measures have different widths, and in the measure
where there are two chords the second chord is printed near the end of
the measure, but it should be printed at the center of the measure..
Thanks a lot, bye!!

Giordano