Thinking about the pickups, if the guitars were late 60s or early 70s, they probably had Gibson T-Tops. Guys like Seymour Duncan and Larry Dimarzio didn't really start making after market pups until around 72 or 73.
As to how they were made, according to this article, they would be Alnico 5 with polyurethane coated wire ~7.5 ohms. That's pretty much the SD-59 recipe, isn't it.
https://musicalilluminism.wordpress.com/2009/04/28/vintage-gibson-humbucker-specs-and-general-pickup-tech/