The fluff for Leviathan is so well written. I checked out your Blog, was there expansions for the main rulebook?
I didnt have the patience to read the Leviathan rules carefully, but I would enjoy more fluff if it was written to that level.
I think the Leviathan Steppe Orcs could easily find their way into Chronopia, the Humans too.
The Dwarves, maybe, but then the steam punk would have to be tonned down.
The Elves, probably not, I think they are too much like Chronopia elves/firstborn so would not really bring anything new.