I measured two of my unused Teflon chips for my 1977 H-16. They measure 1.5 inches, or in metric 3.8 centimeters.
If you try using nylon, I'd watch it carefully. I don't know how well it would deform, before cracking. It also might have a tendency to squeeze out of the bearing. If it fails, just call it a day, and you will probably do little damage to the metal surfaces.
The Teflon chip will deform into a cup shape, usually without any problem. A search of this site's archived topics would be useful to you, as I believe the Teflon chip topic has been discussed a few times in the past.