IF Hong Kong's dedicated Budget watchers are to be believed, Sir Hamish Macleod will deliver a Budget of prudence and soundness on Wednesday. Not for him any showmanship or desire to stamp his mark to leave a clear legacy. The debate about Sir Hamish's Budget is likely to revolve more around what he does not say than what he does. One issue is the question of whether the practice for generating surpluses year in and year out is in the best interests of Hong Kong's residents. The territory is obliged to leave $25 billion in reserves in 1997. The reserves are now roughly five times that amount. Budget deficits have been forecast over the next two years as the Government pours funds into the airport and airport-related projects. But even these are unlikely to make a substantial dent on the reserves. When the airport is completed it will earn significant revenues, filling the Government's coffers. It is already forecast that external debts incurred by the airport development will be repaid within four years of the airport starting operations. Accountant Price Waterhouse says the operating surpluses over the next three years are expected to remain between $30 billion and $40 billion. Consideration should be given to pumping that money back into the economy and the people of Hong Kong.