Doubts Or Concerns About The Authenticity

Well, of course they are. And it is nothing new. Would you think this one is ancient?:

Novicius- I'm taking notes on your fine detective work. Nicely done!

Pehaps, but if « wisdom «  means the refusal to take any risk, wisdom is not very wise. What about intellectual curiosity, passion and learning ? And insurances ? »

Well the thing about running risks is that it may turn out well on some particular occasion, but it will turn out badly on the long run

Jokes aside, please always keep in mind that there are some really high quality struck counterfeit coins out there. Many of them are amazing, and I am afraid many of them I will never be able to recognize as such.

Here seller reputation and experience on ancient coins has vital importance.
As I said, I have no idea who the seller is so I refuse to judge in that respect, but Rufus words are indeed wise. And he speaks from his extensive experience on the subject.

Please I don´t pretend to give you advice or anything, but consider contacting the seller, maybe asking for background, coin provenance, maybe arranging the possibility of receiving more information about the item, looking at it personally if possible, etc.

As I said, I wish you the best with this transaction.
We are talking about an important coin and every precaution you may take is welcome.
(Even if that means letting this one pass and saving the money for another one)

Best.