The head of the Air Force said yesterday that the B1 bomber offers the Reagan administration the best chance to signal the Soviet Union its determination to right the strategic balance in a hurry.

Gen Lew Allen Jr., Air Force chief of staff, laid out his position in an interview even as Defense Secretary Caspar W. Weinberger was pondering what bomber or bombers to recommend the President Reagan for the rest of this century.

Stressing that he would of course subscribe to whatever decision his civilian superiors make, Allen's remarks nevertheless fuel the raging argument over whether the B1, the radar-evading Stealth bomber or both should be built.

Allen said building the B1 now and the Stealth later would fit in with what he understood to be the Reagan administration's intention "to confront the Soviet Union quickly with clear indications of the resolve and determination of the American people to match the Soviet threat and to show that resolve in an unambiguous way prior to resuming arms limitations discussions."

Whether Reagan goes along with the Air Force and builds the B1, which President Carter canceled in 1977, or skips over it to reserve those billions for Stealth will depend a good deal on attitudes toward redressing the U.S.-Soviet strategic balance in the near term, Allen said.

"The B1 offers a way of doing that which is credible and early and which will be noticed by the Soviet Union in a very major way," he said.

The Air Force estiamtes that it would cost about $18 billion for 100 updated B1s, with the first of them ready in the late 1980s, and $22 billion for 100 Stealth bombers for the 1990s.

Critics, including Chiarman Joseph P. Addabbo (D-N.Y.) of the House Appropriations subcommittee on defense, contend that bringing back the B1 would amount to wasting billions of dollars for an airplane the Soviets would be able to shoot down with ease by the end of the decade.

Allen, a soft-speaking, scientific type rather than a lightning and thunder general of the mold of Gen. Curtis E. LeMay, an earlier Air Force chief of staff, took on B1 critics in a low-key way during the interview in his Pentagon office.

"It can penetrate" Soviet defenses "into the 1990s," he said. If that judgment should prove to be wrong, Allen added, the B1 could carry cruise missiles and fire them into the Soviet Union from outside the reach of defenses. Besides that, he said, the B1 could carry iron bombs in non-nuclear wars.

"It really is a most robust addition to the strategic force," said Allen of the B1.

If Reagan tried to build the B1 for tomorrow and the Stealth for the day after, as the Air Force is recommending, he would run short of money for other Pentagon programs, according to several members of the Senate Armed Services Committee. They say the Air Force will have to send Congress a list of other projects it will cancel or stretch out if it is to win approval of a two-bomber proposal.

"The budget is tight over the next few years," Allen said, "but is less tight as one looks out into the future. You may have to delay something for a year or so. But I think it's an oversimplified way to say it that 'You can't have two bombers.'

"I think a better way to say it is: 'If we do the B1, we may have to accept some delays in when we bring in an advanced aircraft to meet budget profiles, or we may have to make trades with other systems.'"

Saying that it is "my solemn obligation" to carry out whatever bomber decision Reagan makes, "and I have no problem with that," Allen added: "However, I did interpret the intention of this administration to be one of showing this resolve and determination quickly, and with a very high degree of credibility. And that seems to me to be a strong argument" for grabbing the bird in the bush, the B1, while working on the Stealth.