Headhunters for the incoming administration are scouting prospects to head the Synthetic Fuels Corp. For John Sawhill, that's good news and bad news. The good news is that it indicates President-elect Ronald Reagan does not intend to dismantle the fledging corporation, set up to promote the production of fuels from coal and oil shale.

The bad news is that it also indicates Sawhill will soon be out of his $175,000-a-year job.

What the administration is looking for, according to transition officials and others, is someone who will make sure the idea of promoting synthetic fuel development doesn't translate into massive government financing of the developers.

Among the possibilities to replace Sawhill are Frank Zarb, head of the Federal Energy Administration under President Ford, and Paul MacEvoy, a member of Ford's Council of Economic Advisers and a friend of Alan Greenspan, a top Reagan economic adviser. Zarb's name also was mentioned early as a potential energy secretary, a natural candidacy for the former head of the Department of Energy's predecessor.

A New York management consultant who was asked by the transition's office of presidential personnel to suggest some candidates for the job said he had offered five or six names. There were academicians in that group, partly because of their credentials and partly, he said, "because $175,000 would mean something to them." As opposed to some of the nation's other whiz-bang energy economists, for whom that salary would represent a substantial pay cut. CAPTION: Picture, JOHN SAWHILL . . . now holds $175,000-a-year job