Wanted: Russian threaded headset.

die nut alone will not work as you are creating new thread not just chasing - it'll need to be in the proper handle so it will locate and start properly,

use plenty of oil and 2 steps forward 1 step back movement

it's forceful to cut 25.4 over what is really a 26.0 steerer, so make sure you brace forks at the crown or low on the steerer

• bracing lower down the forks (i.e. bracing the blades) may bend the blades of the fork as you apply the torsion. so if you go to a shop watch they are doing it right
  
  

Yeah man, got it. Used to have to alter loads of threads on plant machinery when i was a fitter just to get stuff up and running, so i'm well aware that it's a big ask of the tooling. It's kind of a beater so although i don't really want bent forks as long as it rides straight no-handed i'm happy ! All this just for matching lugs eh !