That's right! I switched out the Lancer's chassis for the Charger's! By way of comparison, here and here are pictures of the original builds.
The idea first came to me when I noticed the Arc Node fit equally well on both chassises. I also didn't feel that the Charger's more fluid, dynamic pose suited the model - it looked like he was side-stepping, not lining up the shot he should be taking! Furthermore, I liked the image of my Lancer shouldering into another warjack, bludgeoning it with his shield.
Thus was born this very simple conversion. The biggest thing I did was pin the head, making it so that the warjack was looking over the shield at his target. I drilled the pin into the head at an angle, then filed a little down on both sides - on the left side, to make the head more flush with the body, and on the right, to make the back corner of the head less obtrusive where it stuck out.
I'm really pleased with how the whole thing turned out - the simple conversion proved to me that with the right amount of creativity and thought, unique takes on "unmodifiable" metal models were possible. On top of that, pinning the arms and head was much less difficult - and dare I say, more fun - than I thought it would be.
Also: sorry about the color of the photos! I forgot to turn on the white balance of my digital camera. The photo quality turned out well enough that I don't feel like retaking such simplistic WIP shots, but the pics of my Journeyman Warcaster will need to be redone. -_-;