The OEM needle should either have the number 272304 (in carbs 022A, 087A)* or 273004** (the latter hardly readable) stamped in.
* carbs on: CB550K, CB550K1, CB550K2, also in carbs 627B (CB500-A) and 649A (CB500-ED, G, NL).
** in carbs 069A on: CB550F, CB550F1 and CB550F2