Far better than expected. That phrase summarizes the opening exchanges between the American administration waiting to be born and the aging leadership of the Soviet Union.

Both parties have moved in ways that express a willingness to do business. If events in Poland and the Persian Gulf do not explode, there is a decent prospect the Big Two can even get back on the trac toward an arms control accord.

President-elect Reagan took his stand at a press conference here in Los Angeles. During the election campaign he had repeatedly assailed the pending arms control treaty with Moscow -- SALT II. He had spoken of "scrapping the treaty," which he called "fatally flawed."

But at his press conference he went out of his way to keep arms control negotiations alive. He was asked a general question about "self-determination" for foreign countries under the heel of Moscow. Instead of giving a direct answer, he inserted what was clearly a well prepared comment on arms control. He said:

"I don't believe you simply sit down at the table with the Soviet to discuss arms limitation, for example, but you discuss the whole attitude -- he world attitude. . . . In another words, believe in linkage."

"Linkage" is a term that implies, in foreign policy jargon, insisting on political conditions as a price for arms control agreement. The Carter adminisration opposed linkage. By embracing it Reagan takes a tougher stand -- rhetorically.

But his position is a long way from the kill-SALT prescription so dear to most of his defense advisers. The basic fact is that Reagan is on the move. He is thinking and talking about going "to the table with the soviet Union to discuss arms control."

The Soviet leadership broached its position in the course of ceremonies marking the 63rd anniversary of the Bolshevik Revolution. Previously, the Russians and insisted that the options were either SALT II approval or a new arms race.

A reminder of that came in speech by Defense Minister Dimitry Ustinov at the anniversary parade in Red Square. He spoke of the "danger" of a new Cold War" and of the need for "strengthening the defense capacity of the Soviet State." But a far more supple posture was sketched out for the leadership as a whole in a major speech given the day before the parade by Nikolai Tikhonov, the 75-year-old prime minister who replaced Alexei Kosygin last month.

The Tikhonov speech blamed the recent deterioration of relations on President Carter's failure to "display a high sense of responsibility." It expressed hope "that the new administration will display a more constructive attitude." It said:

"Out line . . . is stable in nature. There are no international problems that cannot be solved through negotiating with reasonable consideration of mutual interests. The Soviet Union is prepared to reach an understanding on the reduction or ban of any weapon -- above all, nuclear weapons."

Wary evolution from past positions, a slow, careful, winding down, is the theme common to both sides. Reagan is inching toward arms control and away from a position of all-out hostility; the Russians are inching away from tough tactics with Carter toward a willingness to deal with Reagan.

Events could easily upset the process. The Russians may feel a need to crack down in Poland. They may find a chance to pick up assets in Iran or other countries around the Persian Gulf. In either case, it truly would be the beginning of a new Cold War, and the Russians would be well advised to pay close attention to what Reagan said about "linkage."

But if the present evolution of Big Two relations can continue, the outlook is not so bad. Tacit accord can be reached to maintain the basic stipulations of the SALT II treaty. Then, without rafifying that document, the two countries can proceed with the negotiations of the geniune cutbacks envisaged for the next stage of arms control -- SALT III.

What all this says is that the tricky business of transition in relations with this country's most dangerous adversary can be managed. The Russians, for the first time in years, now have to organize their behavior toward the United States in the certain knowledge that they have something to gain, and something to lose.