my 96 kila is a 27.0mm with a 27.0mm control tech post.
interestingly though the same 27.0mm control tech post was too narrow for my hei hei which was also meant to take a 27.0mm. it slid right down the seat tube and knackered the decals.
so the best solution is try the post in the frame!!!
lovely bikes very understated and as mentioned as good as an explosif