You have a good bike for this upgrade (unlike most who follow trends I consider more and lower gearing an improvement). The Campy Ergo will handle a triple range easily. You should assume that whatever crank you end up with will need a different BB. If the same crank was used as a triple, compared to it's double config, the usual added driveside BB axle length is about 3 to 5mm. Aprox because as you look at ring/stay clearance the closer to the BB shell you get the more the stay angles in to the frame's centerline, so a complete added ring dimension isn't often completely needed (for the BB axle).

Don't forget about the ders too. Depending on how small a granny ring you pick and how good you are in avoiding some cog/ring combos the OEM double front der might do well. But if the inner is real small or you like to cross chain I would suggest a ft der for a triple. So to with the rear der but now the issue id chain wrap and having a chain long enough to still handle the big/big with minimal droop in the small/small.

BTW I have a NIB Campy Mirage 170 armed triple set (52-42-32) that I have never used. PM me if you're interested. Andy