I recently watched Ted (the movie). I think that was the first time since watching the movie at the cinema back in the early eighties that I thought about it. Back then I thought it was great. I'm not sure I could stand to watch it today...I don't think Flash is really in the public mind - the property is nostalgic, rather than current.
Thirded (if that's a word) Savage Worlds and Slipstream are a good choice for a pulp sci-fi game.Seconded - and I would say "Spot on!"
FWIW, Buck Rodgers predated and actually inspired the original Flash Gordon stuff. Flash was created to be competition for Buck's comic strip.Buck Rogers was a tv show in the 1980s and then an RPG. You could probably re-skin the same set of rules and create a campaign on Mongo...
Look at Conan - by every right it should be public domain since the author died in 1937 unmarried and childless, but somehow a company in Sweden claims the copyrights on it.