Convert from truss to oka, oke [Turkey]

Unit Definition (truss)
The truss is a traditional weight unit, generally equal to 4 stone or 56 pounds (about 25.4 kilograms). The truss was used primarily for measuring hay. In 1795, Parliament specified that a truss of hay should equal 56 pounds for old hay or 60 pounds (about 27.2 kilograms) for new hay.

Unit Definition (oka, oke [Turkey])
The oka, oke [Turkey] is a traditional unit of weight in Turkey and throughout the eastern Mediterranean. The oka is approximately 2.8 pounds or 1.28 kilograms, although its size varied somewhat over the large area formerly included in the Turkish empire.