LIMIT SEEN ON USE OF IRAQ AID FUNDS
World Bank economists conclude Iraq can absorb only about $6 billion in aid in 2004 for its infrastructure needs; Bush administration officials say target can be met from American and international donors; World Bank, United Nations and administration officials are struggling to plan for international donors' conference they fear could be judged failure for lack of pledges; administration official says Spain, conference host, is concerned that United States might delay bid for United Nations resolution on Iraq's future government until after late Oct conference or even abandon resolution (M)

