There seems to be a variance in seat post sizes. The two Triathlon Masters(Aussie model) I have owned had 2 different sized posts.

The first one I owned, was purchased from the original owner, and was a 100% original bike, other than replaced bar tape and tyres/tubes. This had a 27.0 Sakae post.

The next one I owned was purchased from an old couple. Not too sure on its origins, but it had a 6400 group with single pivot brakes, the 7 speed version RD, and had Mavic Open 4CDs, rather than the Araya CTL-370 rims. This bike has a Sakae Laprade 27.2 post in it.

Looking at at the specs on Sheldon Brown, Tange 1 supposedly takes 27.0, but one of mine takes 27.2, which fit perfectly inside. Could it be reaming differences between the years?