This is how I used to play it, many years ago,
with chords in upper case,
and individual-notes-added-to-a-chord in lower case,
with G = F chord slid up 2 frets,
and with Gx = G7 chord without the high e-string,
so that b is the highest note.

  C                   d
  In the Morenos Mountains
                       d          G7    c   c d
  campesinos are planting their fields
              G       e f e          G7
  While the ghost of Zapata rides a horse
        c    d    e  d        C     d
  that can still outrun the wheel
                              d  C7
  There, free in the sky high above,
                d      F     Am  Dm  Dm7 G7
  nearly clear out of sight
             G       e   f        Gx  c   d  C    c d d
  It's the Free Mexican Air Force flyin' tonight