A slam-bang, round-trip, mock bombing attack on Egyptian firing ranges by American-based B52 bombers; expanded joint military exercises; accelerated arms deliveries: is this what Hosni Mubarak needs at this precarious time to consolidate his new presidency?

It's up to him. As a former Air Force commander and faithful public supporter of everything Anwar Sadat supported, he would be expected to appreciate a loud demonstration of America's power (however muscle-bound) to make its influence felt in the region. There is no reason to doubt that he shares the concern of both the Reagan administration and his predecessor over the threat posed to Sudan, the Persian Gulf and elsewhere by the Soviet Union and its surrogates: Libya, Ethiopia, Yemen.

But as evidence accumulates of a widening Muslim fundamentalist conspiracy in Sadat's assassination, he must also be asking himself the same questions a lot of authorities on Egypt are asking:

Did Sadat allow himself to be drawn dangerously into too great and glaring a military relationship with the United States? Did he put too easy a price on peace with Israel, at the expense of the Palestinian cause--and peace with his own people? Did he undervalue the importance of the Palestinian issue to his "Arab brothers," or the importance of their good relations with him?

If the answer to any of these questions is a qualified yes, then the United States has to look well beyond quick military fixes as a way of demonstrating its commitment to continuity in the Egyptian-American relationship. In fairness, Secretary of State Alexander Haig has wisely been at pains to stress the importance of continuity in the Camp David peace process.

But there was more to the Sadat position on Camp David than merely slogging along with the resumed negotiations on "autonomy" for Palestinians on the West Bank. There was also his plea, on his last visit to Washington, not only for the inclusion of the Palestinians in that process, but for the United States to "start a dialogue" with the Palestine Liberation Organization itself.

The inevitability of dealing with the PLO at some point is more easily apparent to ex-presidents and ex-officeholders than it is to those in power, as witness its advocacy in the extraordinary joint press conference by Jimmy Carter and Jerry Ford. We will see how readily President Reagan risks the awful wrath of Israel and its American supporters if the new Mubarak government picks up that part of his predecessor's prescription for Mideast peace, as well.

If the Reagan administration can tear itself away from the Pentagon long enough, it will find over at the Agency for International Development one of those "symbols that move mankind" that Henry Kissinger thought statesmen ought to seize.

The symbol, in this instance, is the Aswan Dam. In early 1956, a deal was all but struck whereby the United States (with $56 million) and the British (with $14 million) would provide the seed money--and as much as $200 million more later on. The World Bank would kick in another $200 million in loans and oversee the project; the Egyptians would furnish the remaining $900 million to complete the job.

But Egypt's Gamal Abdel Nasser had done the famous Czech (Soviet) arms deal the previous year, earning John Foster Dulles' undying distrust. The cotton lobby wanted no more foreign cotton acreage, which was a large part of the point of the Aswan Dam; the power lobby wanted money for dams in the Northwest; the Israeli lobby wanted nothing for Egypt.

And so, crudely and disingenuously, Dulles reneged on the American money in June 1956, and the deal collapsed. An angry, humiliated Nasser had just the pretext he needed to nationalize the Suez Canal, from which action came the Israeli-French-British attack on Egypt--the 1956 Suez war. The Soviet Union wound up building what was then popularly known as Nasser's Pyramid. Dulles' decision was an authentic hinge of history.

The Aswan Dam had its serious ecological repercussions; its hydroelectric power and land reclamation were no match for Egypt's relentless demography. But symbolically, it was strong medicine for the people of a desperately impoverished land.

The piece of that symbol over at AID is a $50 million project to replace 12 metal-fatigued Soviet turbines in the Aswan Dam. The United States has a second chance at a hand in the Aswan Dam--and apparently not by accident. Swedish and Japanese firms competed, but Egyptian officials report that the Sadat government wanted an American company. Allis-Chalmers apparently got the nod.

The day before Sadat died, the Egyptian embassy and AID authorities told me final approval might be only a week away. "We have come full circle in a quarter of a century," said Egyptian Ambassador Ashraf Ghorbal.

It is no big deal, weighed against the $750 million total in economic aid planned for Egypt in the current year. But to Sadat it said something of symbolic significance in terms of Egyptian- American relations and of the needs of the Egyptian populace as well. In its own small way, it would make an important contribution--a useful complement--to the message the Reagan administration is considering sending to post-Sadat Egypt in B52s.