Thank you guys.
@ Walter: the car was ordered for Italian market and it was in Milan since the first days. A whole 52 years life almost in the same territory...
So you mean that probably the original sticker was in Italian.
And I have it in German...
And, after the message of Hans, definitely : none of the labels bought fits to an Italian 230 SL.
For curiosity I attach an image of a label , certainly original, present on the border of the trunk where you can see the message about tyre pressure in 5 languages : german, english, french, italian and spanish.
More : another certainly original label is the red one on the inner surface of the trunk lid : and it's in german only. Hallelujah !!!