Unless it is a full-race engine, 40 DCOE's are fine for a 1600. But I would check the venturi size. The factory carbs for a 1600 Duetto had 30mm venturis.
If I were you, I would consider rebuilding the Duetto's original engine for the Duetto. Sell the 1600 SS engine (surely someone with an SS would pay good money for it!). Then buy a cheap 2L for the track car. The 2L offers cheaper horsepower and really easy to find parts!