I agree it looks like the under chainstay braze on is still there. My guess is a previous owner transferred parts from an older bike and was too cheap to get longer cables or the cables are stuck in the shifters.
Here is a nice source for helping to identify a Super.
Velo-Retro: Colnago Super Timeline
I am a recent convert to the Simplex shifter. Once dialed in, they're very nice. Here is my '82 Super, repainted. I felt like I got a great deal on mine, but it was a lot more than $50!
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N = '96 Colnago C40, '04 Wilier Alpe D'Huez, '10 Colnago EPS, '85 Merckx Pro, '89 Merckx Century, '86 Tommasini Professional, '04 Teschner Aero FX Pro, '05 Alan Carbon Cross, '86 De Rosa Professional, '95 Gios Compact Pro, '95 Carrera Zeus, ‘81 Masi Gran Criterium, ‘81 Merckx Pro, ‘89 Cinelli Supercorsa, ‘83 Bianchi Specialissima, ‘VO Randonneur, Ritchey Breakaway Steel, Rivendell Rambouillet, Heron Randonneur, ‘92 Ciöcc Columbus EL