Converting 8 speed Mavic hub to 9?

I have a set of older Mavic Cosmic clinchers with what I thought was
an 8 speed Campy cassette body on it when I bought them (used) several
years back. Front and rear wheels are 16 aero spokes, fronts are
straight pull laced radial, rears are cross 1 w/ standard 90 bends as
the hub. The cassette installed was (and is) an 8 speed Campy, and
while it fits, it doesn't appear to be what the hub/cassette body was
designed for? I'd like to convert this wheel for use with 9 speed
Ergos but don't have an idea what cassette the hub was designed to use
in the first place?

My LBS is usually pretty good at figuring out my odd stuff but doesn't
seem to know what cassette this hub was built for nor any suggestions
on how to convert it to 9 clickers. As a last resort I could install
one of the Marchisio 9 speed set-ups that work w/ Campy 8 speed hubs,
but I was hoping someone with more knowledge than I could provide some
guidance?

Thanks, MW