Kosten played many tournaments, finishing first or equal first in the following:

In 1976, while only 15, he finished equal first in an event for players under 21.

His best placing was in 1964 when he finished second equal with three other players behind Michael Haygarth.

For teams that finish equal in points, the following rules are used:

Three Italians finished equal first, each with five wins and two losses.

He finished equal first at the Pleven 1987 and Sarajevo 1988 tournaments.

Greater goal difference in matches between the tied teams (if more than two teams finish equal on points).

This gave him 10 votes and was enough to finish equal 11th, despite making just eight appearances.

Greater number of goals scored in matches among the tied teams (if more than two teams finish equal on points).

Balmain and South Sydney finished equal at the top of the ladder, having dropped just one game each.