Is that from gunsight or "target finder"? I like that a lot.
I don't like PTFE that much. I have used it a little on fly reel bearing/brake, but it was not that easy to glue. Also it needs certain surface quality, too coarse is no good, but neither is too smooth. It is also very soft and has tendency to extrude when loaded. Therefore you need a LOT of area. You might get away on top, because you have a lot of surface area there, but I don't like the look of bottom bearing on teflon. I would use metal (or composite) plain bearing. Easy on lubricant, you don't want it on teflon. The good thing is that if teflon sucks, you can go on POM and after that you can go reinfoced composites, and by them you know a thing or two on syntethic bearings.
As you see I'm big on rolling bearings, but plain bearings are great on loads which would brinnel ballbearings in no time.
My 2 erocents,
Pekka