I used a 25.0mm Campy aero seatpost on my 1978 ALAN, but I can't remember which model. Browsing the 'net the posts that look similar are the Athena and C-Record, although I doubt either was available in 1978. I sold the seatpost a couple of years ago to a list member for use on his ALAN, and I hope it's still doing the job.
I rode that bike hard until it broke. The forks worked just fine, but the front side of the head tube split top to bottom. A pothole on a crit course did it in. I weighed about 170 lbs at the time, so maybe I was a little too beefy for the properties of the frame. It was a very cool bike at the time, though.
ALAN offered to repair the frame for free, but the round trip freight cost was more than the frame was worth.
Dave Ross feeling great after 2 rides on the new hip this weekend Portola Valley, California