While this game was being conceived, I have always elected to stay away from retro comics. To me anything before the Bronze age doesn't quite fit the universe that I want to build.
In this universe evil exists, children will be hurt, old heroes will die from terminal diseases, cities will be decimated and the deaths of millions will weigh heavy on the hearts characters. In my observation, that is way too much grief for anything prior to the Bronze age of comics. I'm not quite ready to say that ST & STS will fulling embrace modern comic, but for sure it will not mesh well with the Bronze age designation. Here [thepatronsaintofsuperheroes.wordpress.com] is a good explanation of the different comics ages if you are curious.