I made new blocks when I wasn’t happy with the fit I had gotten on the originals, and I did indeed use Delrin. I believe that’s a great material for this application. There is really not a lot of force on that bearing and it is a relatively large contact surface. As far as outdoor exposure is concerned, the issue is long-term UV exposure. That’s a complete non-issue with floorboards in place. Your aluminum parts do look very nice, and I would recommend perhaps some bonded dry lubricant on contact surfaces. I just wouldn’t want builders to have unwarranted concerns about strength of that part. As I believe has been stated previously, I don’t think that there has ever been a reported catastrophic failure of that bearing from any of the thousands of Kitfox aircraft that have been built.