World Quest rewards only go up to 330 - occasionally 340 for dungeon quests.
LFR gives 340. Warfronts give 340.
Weekly World bosses have a chance to give 355, and 370 for the Arathi boss.
I am surprised to hear you got a 330 from the Timewalking quest though?
That’s why I say it’s fast and easy to get 340. Getting gear above 340, apart from luck with the slot machines than randomly give you upgrades, and the weekly chances, is a matter of doing harder re-made group content, like Mythic-Plus dungeons or Normal or higher raids.
If your guild does raids or M+, that’s one way to get onto the gear ladder. Another might be to find other groups that do content together like