The New Standards can be very good horns. By getting the serial number will help in knowing what year it was manufactured. My former teacher/mentor played one like this for over 40 years (Fred Dart). I think his was 1968 vintage.
From the two pictures you shared, it looks really good. I don't see any dents or dings, but I can't see the back of the horn. Also, you should check the condition of the valves to see if the plating is still in tact and check valve compression by pulling out a slide (without depressing a valve) to see if you hear a "pop". Maybe the seller can provide more pictures for you.
Once you get the serial number, you can check mfg date by checking
this link.