Hmm, so you mentioned two of my top games… Why a rebirth? What’s wrong with the original games, both RQ and CT are still in print. For less of a fire-hose of Glorantha I think works, take RuneQuest 2, Cults of Prax, and the maps therein and have at it. Maybe add in one or two of the early modules (Apple Lane and/or Snake Pipe Hollow). That’s how I played back in the day and it was just fine. If you want more, gradually add more material, ignore anything that contradicts what you’ve established in play.

For Traveller, take Books 1-3 or The Traveller Book or Starter Traveller, rollup a sub-sector and have at it.