Soviet and American trade and business officials ended a week of intensive discussions today, declaring that bilateral commerce may be heading for a modest expansion in the coming years despite the 1974 congressional trade restrictions.

The note of optimism struck at a press conference of officials and businessmen of the two countries seemed appropriate to their efforts to minimize differences and accent positive aspects of the trade relations.

"It is precisely the U.S. corporations, their technology, size and [commercial] possibilities which could guarantee the construction program we are mapping for the Soviet Union," declared Vladimir Sushkov, deputy minister of trade.

His words echoed those last night of Soviet President Leonid Brezhnev, who said the Soviet Union is laying down ambitious new projects in the preliminary draft of the next five-year economic plan (1981-5) and that there is a place in it for American firms.

C. William Verity, American cochairman of the unofficial U.S.U.S.S.R. Trade and Economic Council, asserted that the week's sessions "can well be a turning point in our trade relations."

He predicted that non-agricultural trade turnover could double next year from the 1978 total of slightly more than $500 million, regardless of whether the Jackson-Vanik trade restriction amendment is repealed.

The Soviets reiterated their insistence that bilateral trade, while perhaps improving, can only be unpredictable without repeal of the amendments and extension of most-favorednation trade status to the U.S.S.R. along with expanded financial credits.

The Americans restated their view that nothing can be done on repeal until after the Senate ratification vote on a new Soviet-U.S. strategic arms limitation treaty, expected sometime next year.

Sushkov siad "time has demonstrated" that the amendment is "a failure" that "in no way" has influenced Soviet emigration policies. Jewish emigration is headed for about 30,000 by the end of the year, the highest total since 1973.

The Americans had some suggestions to the Soviets of ways they could improve their trade. A principal improvement, suggested David Rockefeller, president of Chase Manhattan Bank, is for the Soviets to make the ruble into a convertible hard currency. The ruble does not circulate outside the Soviet Union.

"It seems illogical," Rockefeller said, for so powerful a trading country to have a soft currency and not to participate in world monetary decisions.