I’m already violating some of those rules in a small way, so feel free to do so, too. As Matt says, as long as it isn’t crucially game-changing, it should be no trouble.
In my case, I found out a certain piece of kit actually dates from 1979, which was quite shocking to me. But give that similar and actually better (and more expensive, in FFoT points) kit was available in 1970, I feel I’m on pretty solid ground letting this one silde. Imaginations and all that….
We get slapped around, but we have a good time!