Hello !
A long time ago it was easy for me to buy Champion plugs and difficult to buy Bosch or Beru. So I bought N6Y plugs by packs of four (car engine packs).
Lastly I've found a pack unopened with a price indicating it was bought in the near end of the 90s. So today, my R65 runs on N6Y without any problem.
I can't tell if modern Champion are identical to the old Champion I use...
Now, I can't find Bosch nor Champion so I've to buy NGK BP7ES .... And they are quite difficult to get, modern engines using smaller plugs.