If I could afford a new Challenger, it would be cool to make it into a twin of my 73. You can already get the 72-74 side louvers for them. It would be easy to apply a vinyl decal to the tail lights to make four separate looking lenses. The roof could be painted in a black suede to simulate a vinyl top but that might be overkill. I've seen some pictures of new Challengers with vinyl tops and they don't look right.
I highly doubt there's enough interest in the 72-74's to make a grill profitable.