Q.grapevine
Over 100 year old vine gone wild – how far to cut back? Some go one way and then back the other way. What to do? Also, should I peel off bark that is peeling?

Here is a link that will help you with pruning.
Bark peeling is a naturally occurring event in most cases on Grapevines.
You should not peel off the bark.
If however the vine is infected with disease or pests, this could also cause bark to drop from the vines.
https://www.gardeningknowhow.com/edible/fruits/grapes/prune-grape-vine.htm