So you probably found the witch overwold spawner.
You can make a zombie type spawned with a iron spike at the bottom so they get killed and you don't have to deal with vanance or anything.
Now take the chain armour and macerate it, then use the thinkers smeltery to turn it into ingots.
You also get a ton of sticks, redstone, and gold and iron armour so ton of those resources as well.
Gold and iron can be smelted straight into smeltery with an infinite signal you can automate pouring them.
Plus enchantinng books.
Sadly claim chunk doesn't keep the spawned spawning so you actually be near it sadly.

