Best TTRPG system for swords-and-rayguns classic sci fi?

[classicdrogn]

In terms of system or worldbuilding?

Feng Shui might work as a system, it's designed for the type of cinematic action.

I'd say that world/setting details aren't too important except in how the intended style of play affects system design - it's got to work with that Errol Flynn flair, and having the skill and ability frameworks already built around accommodating a need for space-related things like getting past language barriers, astro-navigation, high-/low-/zero-G athletics, etc. is a big part of the "out of the box" factor, but I'm not looking to recreate, frex, the adventures of John Carter specifically.