求懂行的：carved on a sheep monument in England, 8 letters nobody's cracked in 270 yrs (real?)

Saw this floating around and can't tell if it's a hoax or legit so dropping it for the people here who actually know ciphers. It's the Shepherd's Monument at Shugborough Hall, Staffordshire. 18th century. There's a stone carving of a Poussin painting (the shepherds-of-Arcadia one, but MIRRORED, whic……