Did you tension the cable whilst the mech was in the small ring position? Even a tiny bit of slack fucks up the pull distance (again Shimano experience only).
You can also measure chainline to get an idea if your crank is correctly positioned. A road double crank (albeit Shimano, but probably v similar for Campagnolo) should have outer ring at 46 mm and inner ring at 41 mm outboard from the centre of the seat tube.
@fredtc @rhb yep - I've searched everywhere to troubleshoot but even maxing out limit screw, it's still about 10mm short of where it should be..