Daniel Costello, BankAmerica senior vice president for real estate, said the company is having problems finding a buyer for the 51-story Arco Plaza, the building it jointly owns with Atlantic Richfield. One deal fell through last month, and it doesn't appear that the bank will get an attractive offer from three or four other potential buyers, Costello said. Concerns over asbestos, tax reform and other issues are limiting buyer interest, according to Costello. Costello talked with Samuel H. Armacost, BankAmerica's chief executive, and said he was "amenable" to keeping the building for several years. Last year, BankAmerica's sale of its 52-story San Francisco headquarters for $660 million resulted in a $310-million pretax gain in the third quarter.