Toadfrog,
I remember the eyes you are talking about. I never had the specific lure you are taking about, but I had similar ones with that type of eye.
I remember in High School in the 70's a chemistry teacher telling me that NO PAINT would stick to plastic, so I assumed it was a highly pigmented plastic that was applied hot, like a hot melt glue gun for plastic. I melted some plastic at the time and stuck drops on the lures to make eyes but I had problems in getting that much pigment into the plastic and it was hard to get the fusion.
Later I noticed that if the lures got hot the eyes would come off and the pigment would smear, like a paint. I also discovered that my High School Chemistry teacher was not as smart as I thought so it is quite possible that some super aggressive paint was available at the time.
I have not seen that type of eye in some time. Good luck.
https://photos.google.com/share/AF1QipP ... t0Yk4wSkl3