A HIGH-PROFILE reign at the top is to come to an end after three years. Central Plaza's short stay as the mother of Asian skyscrapers will end in 1995. And no longer will a Hongkong building tower over its counterparts in the region. The title is being handed over to the appropriately named Sky Central Plaza in Guangzhou. It will rise 402.5 metres compared with Central Plaza's 374 metres. Developers Kumagai SMC Development Guangzhou Ltd, a joint venture between Kumagai Gumi (HK), Shell Electric Manufacturing (Holdings) and Ringo Trading Ltd, hope the huge commercial complex will be ready before 1996. The total construction area of the plaza is 286,000 square metres. Sky Central Plaza will climb 80 storeys - two more than its Hongkong counterpart. It was designed by a Hongkong firm of architects and engineers. Sky Central Plaza is scheduled to be finished at the end of 1995. A spokesman for Kumagai said: ''The plaza is a gem of a building and an architectural wonder. ''Being the tallest structure in Asia, the plaza will be a monument in the architectural history of China.''