The remit is to inspire them towards being pilots & engineers instead of reality TV stars
Surely the way to do that is to talk about what's there now and in the future, not what happened before they were born.
I am fascinated by aviation history - but it wasn't what got me to university to study aeronautical engineering. It was the exciting current technology and the prospects for the future that I might get to be a part of.
Also, typing as somebody who has done a lot of public speaking - I'd say take the amount you think will fit into your, say, 45 minute talk. Then halve it!
Stuff going on now - Boom, Typhoon, Spaceship II, ISS, FAAM, HypeR? That's probably a full talk, all new and future, and stuff they can genuinely aspire to.
G