A campy crankset with 53/39 chainrings will have a 135 BCD (bolt circle diameter) and will not accept a 34 chainring. It would be cheaper to buy a 50/34 compact crankset with matching bottom bracket of a different brand. And this should be compatible with your D-A cassette. The shifters, if indexed must match the number of cogs and cog spacing of the cassette (9-speed Shimano).