I bought a pair of the 3D printed pin cups, they look and fit great! I thought about painting them to protect the plastic from UV damage, but I'll do it later when I paint my windshield frame and sideview mirrors.
The first picture is comparing my broken original with the new one, using my calibrated finger gauges
The second picture is the pin cup in place. I don't have time to disassemble the header for something like this, so I just dropped them in from the top. My old snap rings had fallen off a few years ago, so my pin cups have been held in place with some double-sided tape as a temporary solution. Now that I have a replacement part, I will use some adhesive to hold them in place.
Thanks again, Kzwxlf! I'll post an update here in a year or two (or sooner if they break).