When a kosher wine is labeled “Not Mevushal”, can one assume that it is nevertheless pasteurized well beyond yad soledet, and the non mevushal moniker is only referring to it being heated to less than 180 F? Is there a difference in this between “top of the line” wines and others? Tizku L’mitzvot!
No. Wine is normally not pasteurized as the heat has an effect on the flavor. Unless it says Mevushal, assume it is not.