Personally, a "steampunk F-122" has been on my project list for several years. However, practical guy that I am, it will have to be something that I can use without compromise.
So, for starters, I will not fabricate "funky" keys and will keep a stock IBM-BS stem+cap system, although blanks, colors, and dye jobs will be on the table. Lesser-used keys around the perimeter might be fair game for "odd" capping.
The thing that makes this completely viable is that the internal assembly screws down into the metal bottom pan, and with these 2 things intact, you can add all the pipes and gears and accessories that you want.
If I could strip the front plate and get it plated in copper or brass, now THAT would be a great starting point!