I like the concept of dark deco + dieselpunk + pulp noir. With the addition of witchcraft and supernatural horrors, it fits right in with the New Weird sub-genre. Moreover, it sounds like a fun, easily digestible while still multi-faceted setting. I look forward to seeing more of this. As for a rules system, I might recommend FATE or the Cypher System, as both are designed to cater to a wide range or games, from pulp noir to superheroes to magic-focused campaigns. Also, both of the above have been created to be agnostic in regards to settings, unlike Pathfinder.