JAPAN OFFICIALS SEE DIFFICULTY HITTING GNP TARGET The government will find it very difficult to achieve its new gross national product (GNP) forecast of three pct growth in the fiscal year ending March 31, Economic Planning Agency officials said. They made the comment to reporters after news that GNP rose 0.8 pct in the October/December quarter, after a 0.7 pct increase the previous three months. For Japan to achieve three pct growth in 1986/87, GNP in the January/March period would have to grow 2.6 pct from October/December, the officials said. The government lowered its GNP forecast for 1986/87 from four pct last December.