Wow.. Scott was all over the place.

L67 was available in the Monte in both 2002 and 2004. No motor worries.
Trans however... the valve body, pressure switch and channel plate are most likely the difference, besides the internal vs external pnp. I'd have someone like Scott or Iceman use a DHP to start with an 02 L67 Monte bin then drag the 04 Monte L67 trans onto it. Then stuff an external pnp you pickup super cheap from a junkyard on it and poof. All set.