I agree with the Henford Vote. Much as I love Windenburg, it does have the modern area that kind of takes the timeless immersion away. Henford's town is more believable in that way. And it would probably be generally easier to use for that gameplay theme.
But you could still use Windenburg, I think. In my game I've replaced the lots on the modern side for older looking buildings and mostly try to play in the older areas anyway. Windenburg is the largest Sim world, it has the most lots (and the ruins too!) so eliminating the modern section from gameplay still leaves a normal sized world to play with if you really wanted to use it.
I'd also say Forgotten Hollow and Glimmerbrook, but they are quite small so there wouldn't be much to work with unless you used them as extension villages to visit. Tartosa maybe would work as well, though I don't have that world, so I'm not quite sure.