Yeah, if you're making a Fallout game that references another time period - a la the 80's - then you're kind of losing a large part of what makes a Fallout game, a Fallout game. I mean, you can make a post-apocalyptic game where everything looks like you blew up 80's Americana - but if you're going that route you probably might as well just start up a whole new IP.
If you want to explore such a world, you may want to pick up a copy of the Twilight 2000 RPG (as in the pen and paper kind). I think it was written pre-berlin-war as It sees a Unified Germany as being one of the early dominos leading to WW3, and a US torn in two between the Civilian administration, and a military administration that doesn't recognise the legitimacy of the former.
I always loved that game. They did make a computer game of it way back in the day, which (at least at the time) I thought was pretty decent - it played a lot like the PnP game, at least.