"This is a statue of carp in bronze, once a bronze colossus, laid to rest by the dwarf Urist Geshtartosid."
The masterful bronze statue (by an unknown artist) dropped by a bronze colossus should become an artifact, primarily for historical purposes.
In technical terms, the ITEMCORPSE of a histfig should still be a legendary object. I could see it also gaining the "all craftsmanship is of the highest quality" descriptor.
Since there's a direct and sole line of continuity from a creature to its ITEMCORPSE, I think it would be fitting for the artifact to use the same name. Certainly would add a bit of horror to modded medusae that turn your dwarves into actual statues.
This would nicely complement the other types of artifact made from living beings, fell mood masterpieces and saintly relics.
I'm not sure how writing objects would behave if dropped this way, but a book might contain a summary of their life story and a slab could be automatically engraved with their memorial. It might also be good to leave writing objects out of the whole itemcorpse artifact system?
There might also need to be a baseline "notability" threshold for a histfig to have when offsite so that a populous ITEMCORPSE race doesn't flood the history of artifacts in the world. If not already extant criteria, megabeasts, skill masters, and nobles that demand special burial should all pass this.