PRESIDENT REAGAN. President of the United States Ronald Reagan. How does that sound to you? There is a certain ring to it. In any event, you may have to get use to it: The way things are going President Jimmy Carter may be moving back to Plains.

If Reagan does take over the White House in January 1981, it will be hard for some Democrats to accept.After all, with Reagan you get not only the former California governor, but a whole system of economic advisers that includes Arthur F. Burns, Milton Friedman, William E. Simon, George P. Shultz, Herbert Stein, Alan Greenspan, Charles Walker and Casper Weinberger.

In addition, Reagan has been listening to far-out theorists, notably Prof. Arthur Laffer (of the Laffer Curve) and Jude Wanniski, a former Wall Street Journal editorialist. Wanniski and Laffer have been labeled "wild men" even inside the Reagan camp. Their hard-line ideology, including a return to the gold standard, turns off many mainstream conservatives.

There is a generous further sprinkling of aides from Washington's conservative think tank, the American Enterprise Institute. That's a heavy dose of right-wing Republicans, many fresh in our memory from the Nixon-Ford past, ready to chop Big Government down to size, while affectionately stroking Big Business with huge tax cuts.

Adam Smith is not around to provide the intellectual underpinning for a Reagan administration, but Bill Simon will serve as a close carbon copy.

WANNISKI'S AND Laffer's influence appears to be fading as Reagan chances for the presidency improve, and he attracts some of the better-known names in the Republican establishment.

"What you're apt to get," says a top Reagan adviser, "is a surprisingly conventional group of censervative working advisers in a Reagan administration."

Greenspan, who headed President Ford's Council of Economic Advisers said in an interview that he doesn't see any "fundamental differences" between Ford and Reagan.

But how much difference would there be between Reagan and Carter, who has disappointed many Democrats, pursuing a recession as an antidote to inflation? (Privately, a top Carter aide now expects the April-May decline to be the sharpest two-month slide in post-war economic history.)

It is true that Carter has had a decent record in the management of federal regulatory agencies, and that in the face of considerable pressure, he managed to resist the most virulent forms of protectionism. There is little comfort to be derived from Reagan's few decipherable campaign pronouncements in these areas.

But in terms of overall management of the economy, there is probably little to choose between Carter and Reagan.External world conditions will probably have more to do with the shaping of macro policy than whether the new chairman of the Economic Council has the blessing of the Brookings Institution or the American Enterprise Institute.

Moreover, under the system of checks and balances, Congress can be expected to temper the zaniest ideas from any chief executive.

Martin Anderson of the Hoover Institute, who may be the closest of all of Reagan's personal economic strategists, said in a telephone interview that Reagan would establish "a comprehensive economic policy early on, and stand by it. You need a constant and stable policy. The average person or investor ought not to be worried about waking up every morning to find the policy changed."

That's a telling dig at Carter's in-and-out policies. It cannot be argued that CEA Chairman Charles L. Schultze has devised a brilliant economic plan for Carter in the past 3 1/2 yers, or that Budget Director James T. McIntyre will be missed. The inflation-fighting accomplishments of Robert Strauss and Alfred E. Kahn had best be forgotten.

THE WORST MARKS of all have to be placed next to the name of Treasury Secretary G. William Miller, Carter's principal economic adviser and spokesman.

Miller, who predicted a turn in interest rates that never came when he was chairman of the Federal Reserve in the fall of 1978, failed to get monetary policy under control. As secretary of the Treasury, he has been a further disappointment, announcing the nation was half-way through a recession before it had even started. He promised a tough line against a Chrysler bailout -- then caved in.

Most recently, in a National Press Club speech, Miller announced that the federal government would have to borrow virtually no new money beginning in April. This week, the Treasury admitted that it would have to borrow $11 billion to $15 billion, just in the next few months.

"Miller's problem," says a former close associate, "is that you can't brief him. He thinks he knows it all, and stops you before you can get started." In retrospect, Carter's most competent advisers dealing with the economy were fired or left voluntarily.

So what is there to fear from a Reagan administration? Plenty. But you have to ask -- compared to what? John Anderson has cited Reagan's militaristic posturing, which might get us into war. But are the dangers of war less under Carter? In a second term, unrestrained by not having to face the electorate again, and seeking to make up for the miserable period behind us, Carter might run off in dangerous directions. But a victorious Reagan, anxious to demonstrate for the history books that he doesn't have horns, could hardly be as bad as he sounds on the stump.