I do not believe this is a paper phenolic laminate. I believe that
the material used in both the original and PPCo replacement valve
guides was "vulcanized fiber". This material is still used to make
"fiber" washers. A thinner version, gray in color, used for electrical
insulation is commonly known as "fish paper".
The material is less brittle than paper phenolic laminates, and
I believe that it is easier to punch. Here's a link with more
A little Internet research turned up several sources for vulcanized
fiber sheets including 0.031", 0.047" and 0.062" thicknesses.