You should make a datapack for mob head collection that requires the decapitation datapack. Then there are SO many more head options to collect.

https://www.planetminecraft.com/data-pack/decapitation-1-15x-more-mob-heads/

I tend to be a collector so I love using the decapitation pack in my maps... and if you DO expand your mobhead advancements, I would probably include them as well ;)