I can confirm that - the brake blocks for the 1999 9-speed Athena brakes on my Basso and those on the 2004 10-speed Chorus on my Cannondale are not compatible with each other.You'll want Campag pads for your new caliper and you will also need to check the groupset and year, as they vary.
If you already have spare Shimano brake shoes/blocks, try fitting them and see how you get on!It's an early Athena btw,I can see how some pads would'nt fit
some shoes,but replacing the whole shoe the only thing that could be different
is the size of the mounting bolt surely???