I'm pretty sure that the F14, in common with most US Navy jets of that time, delivered permanent 100% oxygen (and maybe they still do?).
Unfortunately 100% oxygen doesn't stop airsickness.
Since the mid '50s all USN ejection seat equipped aircraft did not use console mounted O2 regulators and instead used mask or torso harness mounted mini-regulators which always deliver 100% oxygen.
The MIL-R-81533 mini-regulator built to the CRU-79/P specification was active from the late 1960s thru early 2000s. So that is what would have been mounted in the Topgun Tomcats, as well as the A-4s. And they deliver 100% oxygen.
And yes, 100% oxygen does not prevent motion sickness, as Tom Cruise experienced, as well as any of the numerous civilian folks who have flown with the Blue Angels in their A-4s and F/A-18s. And BTW, Mercury, Gemini, and Apollo all had 100% O2 environments and the majority of astronauts still got sick, just as they did in the Shuttle and Space Station which have a nitrogen/oxygen environment.