MOROCCO'S King Hassan II begins an official 48-hour visit in Washington today with a recently improved human rights record undertaken for the occasion.With the gestating Western Sahara referendum process, the proposed Middle East peace conference, and economic development on the king's mind, Moroccan officials insist human rights should not be high on the visit's agenda. Yet Moroccan observers say an ongoing evolution in the country's attention to human rights, and several recent royal gestures in specific cases closely watched internationally, show efforts by the the North African monarch to smooth relations with Western partners. "Hassan is a very intelligent leader; he can see the world is changing around him, from the Soviet Union to his own back yard in Africa," says one Western observer of Moroccan affairs. "The king wants to have the West in his camp." For Morocco, that means particularly Washington and Paris. Both capitals have pressed the human rights issue with the Rabat government, and both are now indicating satisfaction with recent efforts. "We're very gratified by progress in the human rights area," says a US State Department spokesman. The State Department says Morocco has released 435 political prisoners since 1981 - the "vast majority" released since June of this year. Human rights organizations both in and outside Morocco, as well as government officials, point to an "evolution" of the issue. Amnesty International notes progress, but says Morocco still holds several hundred political prisoners. Since spring, Morocco has taken a number of steps to improve the justice system, especially concerning trials against citizens accused of crimes against the state, and to clarify conditions for holding suspects under observation. "A certain number of positive measures have been taken," says Abdelaziz Bennani, Moroccan Organization for Human Rights vice-president. "They are still insufficient, but we are encouraged by the progress." Such talk of progress is likely to win Hassan points as he stops at the White House and Capitol Hill, and meets later this week with US business representatives. Morocco is fond of pointing out that it was the first country to recognize the United States more than 200 years ago. And as it moves towards next January's UN-sponsored referendum to settle the Western Sahara issue, and a planned move to full convertibility of its money in 1993, Hassan is keen to see those historic ties strengthen.