Some K&B engines used Teflon wristpin pads, but IMO, they didn't last terribly long, so keep that in mind and make more than you think you'll ever need. A lot of older engines used brass pads, of course, but I would opt for plastic. There is a graphite impregnated version of Delrin that would be my choice...but I don't remember the name of it. I machined bushings from it, about 40 years ago, and it was nice to machine (Hardinge chucker) and quite slick.
By "graphite", I mean the lubricant type graphite, and not the carbon fiber type graphite. I wish folks wouldn't use the term "graphite" interchangeably with "carbon fiber". Fishing rod makers are the WORST on this.
Steve