Has anyone ported over ghosts (the monster type) to ACKS?  I'm curious as to how you would handle it.

Honestly, I've been exploiting the fact that "ghosts" aren't clearly defined in ACKS to make them mysterious.

As far as my players are concerned, ghosts are clearly supernatural, can't be touched (at least with mundane objects), they often haunt specific places, they rarely realise they're dead, they appear to have obsessions based on how they died or what they did in life... But they don't have easily-researchable powers, their motivations are rarely obvious, and their personalities and sanity vary wildly, just as ghosts in ghost stories do. (This only works because I don't make ghosts that are likely to become combat encounters.) My players have mostly been using the ghosts they encounter as sources of information about the places and times in which they lived and died.