Last parts I needed for front fork assembling arrived recently, so at last I could put all parts together.
I also refreshed look of upper plugs and slightly modified them. It seems that this very fork have never been disassembled before, but it turned out that lock nut of upper plug in one of fork legs had already stuck. Plug has very narrow ledge for 17mm wrench and when I tried to unscrew that stuck nut, the wrench slipped and slightly damaged ledge. So I grinded ledges on both plugs to fit 14mm wrench (which is common) and I also made ledges wider to avoid issue with wrench slipping in future.
To avoid any issues with polished aluminum I assembled fork with outer tubes wrapped in rugs, which in their turn were fixed to rubes with reusable plastic ties. it worked like a charm and further assembling went without problems.