What would be a good held item for my Houndoom?

It has maxed Sp. Atk and high Speed (Special Sweeper)
-Flamethrower
-Dark pulse
-Hidden Power (fighting)
-Overheat

I was thinking Life Orb but since it will be dishing out so much damage, do you think a Shell Bell would be a good Idea? Or maybe Black belt cause it’s the only move without STAB. So yeah, what do you think?

yeah i would recommend giving it a shell bell or a charcoal since it has flamethrower and overheat it raise the power even more.

hope i’ve helped