In article ,
wrote:
Coming out of lurker mode here to see if I can get spoke lengths
for current (9-10-11 spd) Campy Record hubs, 32 hole, going 3-cross
to Ambrosio Excellence rims. There seems to be some uncertainty on
their ERD. I've been on tubies for an age and am hopelessly behind
the times.

As Andrew Muzi has advised, measure the ERD of the rims you have.
The online spoke length calculator I often use:

https://leonard.io/edd/

lists two different measurements for these rims. So, for the rear
hub, you're likely to want 292mm & 294mm spokes for one measurement
and 294mm & 296mm spokes for the other measurement. That's if I've
picked the right hubs and you trust online spoke length calculators.
Certainly the above spoke length calculator has worked for me on the
times I've used it.
--
Dennis Davis