David Stockman, 34, is the man of the hour in the Reagan camp. As the incoming director of the Office of Management and Budget, the numbers-oriented Michigan congressman has sold Reagan a blueprint for getting control of the federal budget.

"You don't have to take every number in it as gospel," says a Reagan insider, "but it outlines the general fiscal strategy."

Under the catchy title "Avoiding a GOP Economic Dunkirk," a scenario authored by Stockman with the help of New York Rep. Jack Kemp calls for declaration of a national economic emergency, with Congress clearing the decks for 100 days to enact a recovery program.

The word from the Reagan camp is that Stockman and Kemp are destined to be key figures in the new economic policymaking framework. Kemp, of course, is co-author of the Kemp-Roth massive tax-cut proposal that Reagan has already endorsed. Stockman's contribution to the developing strategy was to pinpoint in graphic terms the places where Reagan can make dramatic budget savings.

Stockman has been totally absorbed for a long time by what in 1975 he called "the social pork barrel." In a piece in Public Interest magazine, he argued that the nation was not getting much bang out of the buck it spent for "social pork barrel," whatever may have been the intention of the Great Society that spawned the programs.

In practice, he maintained, these programs benefit the "haves" rather than the "have-nots." He pulled no punches. For example, he wrote that many congressmen "admit to holding noses" while voting benefits for veterans "who do not even have a hangnail" to show for their experience in uniform.

As for cancer research, Stockman observed sarcastically that, despite billions spent over 15 years, "the therapeutic preoccupation of the medical guild" had had no noticeable success in cutting cancer death rates.

Can Stockman translate his hard-nosed philosophy into bottom-line results for Reagan? "He may have too optimistic a view on what can be sold to Congress," says a liberal Democratic budget expert, "but he's hit the right categories where there are potential savings. In other words, this isn't bull. You have to take it seriously."

For fiscal 1981, Stockman's budget-reduction goal is limited to the relatively scanty savings that might come through a hiring freeze and from cutbacks in agency travel, procurement of federal equipment and outside contracting -- not more than about $15 billion.

Reductions that Reagan earlier thought might be achieved in later years are trimmed back. Where Reagan's Sept. 9 projections worked out to $65 billion to $90 billion in budget reductions for fiscal years 1982 and 1983, Stockman puts the target at "reducing federal domestic programs levels by $30 billion to $50 billion per annum in the fiscal year 1982-83 period."

More significantly, where Reagan was talking vaguely about waste and inefficiency, Stockman lists specific categories, and frankly goes after every "entitlement" program in his 1975 "social pork barrel" list except for Social Security and Medicare.

Here's what would happen (beginning in 1982) if Stockman has his way:

$2.5 billion to $5 billion reductions in $25 billion worth of annual spending for government construction projects, including highways, mass transit, airports and public parks.

$10 billion to $20 billion in $100 billion worth of welfare programs, covering everything from school lunches to unemployment compensation.

$8 billion out of $25 billion in various work programs that Stockman identifies as "low-priority"; that is, ineffective. These include CETA (the Comprehensive Employment and Training Act), UDAG (Urban Development Action Grants), impact aid programs and expenditures for the arts and humanities.

Another $10 billion to $17 billion would come from clamping down on a host of federal credit and lending programs for housing, farm, small business and other enterprises.

None of this will be easy. Mayors of American cities and leaders of minority groups threatened by a one-third cut in Stockman's "low-priority" programs are likely to go up the wall.

Nonetheless, Stockman has answered the oft-repeated question: where would you make the budget cuts? There, the fight in Congress can be joined. Although there is unanimous agreement that it is important for Reagan to put some economic measures inplace quickly, not every Reagan adviser is sold on the wisdom of declaring a national emergency.

"Presidents don't declare a national emergency," says a key Reagan adviser. "They identify the existence of a national emergency, and shouldn't do that until they have the action programs necessary to deal with it."

The danger, thus, is that a Reagan emergency declaration might equate to exhortation rather than results. Stockman acknowledges that under his plan, the new administration won't get everything it wants.But he's convinced that a sweeping, bold approach will in fact begin to control the "social pork barrel."

Surprisingly, some experienced Democrats think he's right.