I thought the M6 as well, but being a three-emitter light, you’ll be a bit short of your desired 4k lumens. Too much variation in the King-style lights now, so I wouldn’t recommend any of those.
Maybe the Solarstorm T4? I don’t have one so this isn’t a recommendation… 4-emitter but only three cells though, and would need some modding to get to your desired output. Probably a set of XM-L2 emitters and a Fet driver from Richard, if it fits…