The problem I've found with historical fiction - even pseudo-historical - based in "real world" places is that the further back in time you go, the more documentation you need for your theme. It also gets I think harder for people to just come in and play - the more documentation/theme files you have, the more people have to read until they feel comfortable, and that can turn people off. And then you have the players who think they know everything about that era and become like, the czar of YOU ARE PLAYING THIS WRONG and ugh, those people make historical fiction games really difficult to play.
It's also I think hard to introduce a cultural era that a majority of people have little to no knowledge of. Which means that you're going to have people unintentionally being ignorant of the times. Which means you're going to combat that with more documentation and that's going to give people more things to read and it's kind of a vicious balancing cycle and you're still going to have people being culturally ignorant unintentionally (or even intentionally).
Anyway that's just my two cents. Steampunk Lord & Ladies sounds like it'd have a good mass appeal, I would just be really thoughtful on the setting (and I would, honestly, probably go with everyone else's suggestions and make your own world at that point)