Omega Speedmaster DATE Automatic Chronograph for $.1,882 for sale from a Trusted Seller on Chrono24

I'm looking to purchase this Speedmaster, the seller has informed me it is sn# 58176820. My questions are is this an authentic Omega and has anybody dealt with this dealer? Thanks for all replies.

Atelier Orologiaio di GSP S.r.l.
Via Cesare Correnti,3
20123 Milano MI
Italy