In the 80s, I had a Campy Super Record equipped Gianni Motta with Columbus SL tubing with a 27.0 set post. Some SL frames were 27.2 and some were 27.0.
Just a couple months ago, I had a friend ask me if I still had any 27.0 seat posts. He was rehabbing an early 90s tandem from a famous maker that needs a 27.0 stoker seat post.
__________________
“Train hard until your legs are tanned, then keep going until the shape arrives.” -Jolanda Neff