In reportedly picking fiscal conservative Jack Kemp as secretary of the Department of Housing and Urban Development, President-elect George Bush at first glance appears to have made something of a mismatch. The HUD agency, with its social programs, is hardly one of those places where a hard-line conservative would be expected to feel at home.

Yet on closer inspection, appointment of the New York congressman may not be such a departure from Kemp's interests after all. Kemp, who gained national recognition for his conservative fiscal policies, has often abandoned conservatives on some social issues - the kind HUD deals with.Although he was the moving force behind President Reagan's 1981 tax cut, a strong advocate of the administration's military buildup, and a supporter of aid to the Contras in Nicaragua, Kemp was less doctrinaire on housing for the poor.

He has favored inner-city enterprise zones, has suggested the use of housing vouchers for the poor, and has supported programs to allow public housing tenants to buy their dwellings at low cost. All of this indicates a sensitivity to housing problems for low-income Americans.

The selection of Kemp may be seen as a signal from Bush that he supports such self-help programs for the poor. It also may be a signal for a more active federal housing policy under a Bush administration.

The choice of Kemp comes in spite of the fact that he left Congress after 17 years to run as a GOP candidate against Bush for the presidency. However, the former pro football quarterback's campaign never got off the ground. Later, his name was prominently mentioned as the vice presidential running mate for Bush. But Dan Quayle eventually was the Bush choice.

Despite these disappointments, Kemp appears willing to support Bush policies. And the president-elect clearly is continuing his efforts to build bridges to former opponents in his own party as well as among Democrats.