On my NOS Schwinn Paramount 50th Anniv. Frame, and my build-up last
year, I went with all 2004 Record Drivetrain Components. My rear
dropout spacing was just a tad over 128mm (Something like 128.858mm with
a Dial Caliper)

Just a very slight stretching was required with my fingers, and slight
finger pressure , which I don't think will ever be a problem for me, and
shouldn't be for you.

While my Wipperman SS Chain, and smallest cog of a 13-26 Cassette
appeared sort of close to the right rear dropout on this 1989 Frameset,
so far I haven't had any problems.

I'm hoping Peter Chisholm will answer your question about the
dating/upgradeability of Campy Veloce Ergos. He's the Campy Expert
here.
Mark