If I were you, I would not use Adwords if I'm using a PBN.
You have to remember that your number one job in maintaining a PBN is to avoid any sort of footprints.
If you drive traffic using Adwords, Google might spider your target website and this might lead back to your PBN.
I know I sound paranoid here but never underestimate the kinds of signals Google picks up on.
Unfortunately, a lot of people who try building PBNs, often do so in a sloppy way.
Somehow, someway, they overlook some important detail and Google picks up on that.
You don't want to find out the hardest way possible.
You don't want to lose your target site.
Either you do only PBN or you do PPC.
I would not mix the two.