System recs for a post apoc/Trigun campaign

I'm looking for a system for a Trigun/Anime/Western type of campaign. My players will be legendary figures who have retired and they get the band back together. So I want them to feel powerful with some hiccups here and there, have guns and weapons. I don't want to do space travel or ships, it will be on one planet.

Looking for low crunch as well. Lower than DnD5e, we have been enjoying Dragonbane, if there are any systems with that OSR feel.