Spiderman is an awesome looking machine, and I have a thing for Superhero themes, lucky indeed.
Well worth the effort to clean up.
How did you plan to make your stencils stick on, or cardboard / timber?
Boots
Stencils will be vinyl mate... see here..
www.flipperescue.com
Would you get the same effect with vinyl stencils?
Originally in the factory they would have used steel stencils / templates with a timber backing for stiffening.
This would have allowed them to be used over and over again for a production setup.
Vinyl wouldn't give any edge overspray like the originals did, although probably the manufacturers didn't intend to have overspray but they did.