In that case, I'll go Mexico. The Super didn't have crimped tubes, and I do not think this is an early Master. Also, at least some Mexicos had a bridgeless bottom bracket (whereas all the Supers I've seen have the bridge). Also, the Supers didn't have "COLNAGO" stamped on the top of the bottom bracket shell like yours.
Is it resprayed? I've not seen the chrome go up the seat stays in that way.
One thing to bear in mind is that the output of the Colnago factory in the early and mid-80s was rather variable in detailed spec (I'm not talking about quality, which is another matter...) I don't know if this reflects an inherent randomness in the production line, or responses to requests from specific dealers/customers. It seems to me that you could order pretty much what you wanted. So "Super", "Mexico", "Master" are more like general ideas rather than a specific frame spec. Which is what makes it fun...
Bottom line is whether it rides like it should. If it is genuine (I'm not ruling out the possibility that it could be a ringer), it will have great geometry and will be a sweet ride.
I forgot to mention that the top tube and down tube are not normal round tubes, but pressed in the form of a leaf.
EDIT: I have seen some Mexico-frames with same kind of tubes. Does the Super have those too?