Struggling with System.

Hi, I was writing a campaign setting that was meant to be a heavy metal, sword and sorcery, Robert Howard style setting.

Trouble is I'm stuck for a system, initially I went with DnD 5e just cos it has so many tools for making monsters and encounters, but then I picked PbtA as a particularly troperific system.

Now I'm kinda stuck, cos PbtA doesn't seem to have as much meat on it. Anyone have any advice or suggestions for systems?