Of course you can mention Villiers here Ron. Even Douglas made a Villiers powered machine. The first year of the Douglas Bantam was Villiers powered before they made their own two stroke engine. This is the top Douglas on my shopping list, followed by the EW of course.
Anyway, gudgeon pin end pads. Villiers used a 1/2" solid gudgeon pin with bronze endpads on all their engines for donkeys years. I've never found a pre 1940 engine without them. I don't know when they finally dropped them. All with a little pressure relief hole as Leon says. From memory it is 1/16" but don't hold me to it.
Teflon was used for end pads as well but the only examples I know of were in American competition pistons where life expectancy and usage would be very different from what you are aiming at. Bronze works quite well and is easy to machine, why change?
Cheers,