I know that I have a rather particular taste, but my dream mod would extend the game's timeline to 15 February, 1763, immediately after the end of the Seven Years' War, that way the player can experience and shape not only the victorian era, but the entire age of revolutions, in keeping with the game's themes of social upheaval and technological progress.
Plus, since it starts after the conclusion of the war, the player would be able to slowly immerse themselves into the world of the late 18th century, without having to worry about waging a full-scale war from the very beginning of the game; there would be time to build to that, and potentially change the course of the revolutions, or create an alternate Napoleonic Wars, or even prevent the Napoleonic Wars from happening through shrewd gameplay. The possibilities are endless.
It's not quite a conversion mod, but it'd definitely be a hell of a lot different from vanilla.