Maurice Barboza, who dreamed of a memorial to honor black soldiers of the Revolutionary War, thought he had leapt the biggest hurdle 15 months ago when President Reagan signed a bill authorizing construction of such a monument.

Barboza knew there was more work in store; he just didn't know how much.

Since then he has quit his job as a Washington lobbyist, sold his home in Prince William County and thrown himself full time into his quest, which will involve more battles in Congress and a drive to collect more than $4 million to make the monument a reality.

Barboza believes the nation needs the memorial to "sweep away all kinds of stereotypes of what blacks were like at the time of the Revolution." Barboza said that the "false notion is that blacks were all slaves, that they did nothing to win their own freedom and made no positive contribution to the development of their own country."

He noted that 5,000 blacks fought in the Revolutionary War.

Since the bill was signed on Oct. 27, 1986, Barboza and other supporters have set up The Patriots Foundation, which is about to launch a fund-raising campaign to collect the money to build the monument, which has not been designed.

The foundation is lobbying in the House and Senate for approval of a resolution to place the memorial on the Mall. Shortly before the memorial was authorized, Congress, in an attempt to limit the growing number of monuments on prime national park land, set up a complicated process for approval.

In a lengthy and complex process, Barboza's group gained approval from Interior Secretary Donald Hodel for a site in what is considered the prime area. Now, Congress must approve the resolution by April 7, according to Barboza, or the group will be forced to go back to square one.

If they succeed on Capitol Hill, Barboza said, "We are not out of the woods yet. We have to go back to the secretary and make a case for placing it at a specific site." Foundation leaders are studying several locations but have their eyes on a site at Constitution Gardens between the Lincoln Memorial and Washington Monument.

Barboza said another hurdle is psychological. "Many people think, 'What role can a memorial play?' " he said. "But then they recognize that if a person does not understand himself, his history or what his potentials are . . . it does not matter how many opportunities he has, he cannot take advantage of them."

The memorial, he said, will "send a message to historians, to teachers, to Americans who have false notions . . . and to black people themselves . . . that blacks participated in the Revolution and struggled for freedom and the principles on which this nation was founded."