Of course it started life as a shotgun, no-one would make or have made a double rifle in 375H&H and cover it in game bird engraving. I'm surprised that Elmer Keith of all people would bother with a shotgun convert, nicely done but not exactly what I imagine a "connoisseur of fine double rifles" would own.
The few Sarasqueta shotguns I've seen have been pretty average as Spanish guns go but there may have been some higher spec ones built. Who knows if the timber is original or upgraded when the conversion was done.
Agree with everything Waidmannsheil has said, good gun to have but 375 Flanged would have been the icing on the cake.