Nicely done! Even though it's too late for this restoration, I have two suggestions you can try for future projects involving decals.

Instead of using an Xacto knife for cutting the decal/stencil material material, consider using a scalpel. The blades remain sharper far longer than an Xacto blade. I've found that as the Xacto blades dull, they tend to pull/stretch the decal/stencil material rather than cut it. You can get a scalpel handle and 100 blades for about $5 on Amazon.

I also use a fixative on my decals so that the ink stays put either when in the water or when cutting. Same principal as the light clearcoat you applied on your playfield after painting a color.

Eight Ball was the first pin I restored many years ago. It's still in my collection.

Again, nicely done. Good luck with the event!

Congrats! Awesome job, I'm sure the buyer will be very happy.