Wow! Any idea what caused them to get to that point?
I'll be honest, they look like they've been neglected big time!
I've never had to address something that extreme so I'm hoping someone else can chime and assist.
I will throw this out there though: Naval Jelly
I've used it to restore completely rusted chrome [quality] socket/wrench sets to heavily rusted bolts/nuts. If you do go this route, I do STRONGLY recommend applying it in a well ventilated area and with gloves on.
It's an amazing product that should sell for a lot more than what it does.
It may just be your savior.