Is it ok to edit a public domain speech? Let me try to explain the project I'm working on. I'm a volunteer for a high school engineering competition, and the past couple of years I've produced a pro bono commemorative video to show at the competition.

This year I want to use the audio from JFK's "go to the moon" speech as a voiceover track, but it would be weird to include references to soviets and war interspersed in the parts of the speech I want to use. 

So, my question is: is it "ok" to selectively edit out the parts that aren't relevant to today's society (as in, taking artistic license), or is this considered inappropriate?

The video won't be shown outside the event, but I don't want to do something considered "wrong."
Public domain material isn't subject to any restrictions -- legally you can do anything you like with it. It would be respectful (but not required) to honor the intent of the material and not distort its meaning, and to credit the source.