When Halacha says that a Kohen should distinguish between all the Hebrew letters in Siman 128 Seif 33 from where it says "similar examples":
מי שאינו יודע לחתוך האותיות כגון שאומר לאלפי"ן עייני"ן ולעייני"ן אלפי"ן וכיוצא בזה לא ישא את כפיו:
One who does not know how to enunciate letters, for example one who pronounces Alephs as Ayins or Ayins as Alephs, or similar examples, should not perform the priestly blessing.
What pronunciation should the Kohen give to each letter, if he wants to be strict in Halacha?
Would historical accuracy matter even though it is not mentioned in the text. However it is impossible to even know what was the historical pronunciation and so he should just stay with his traditions' way of pronouncing?
Or would textualism matter and thus as long as the Kohen distinguishes between the letters even though historical accuracy is disregarded because either way it is impossible to be 100% sure what was the historical pronunciation? If so would would be the most appropriate way for the Kohen to distinguish if there is such thing for being appropriate? Would it be by adopting the Yemenite or Baghdad system or some other way?