About a year ago, Virginia Lt. Gov. Charles S. Robb sat down with David McCloud, his executive assistant, in a cramped state office in a Bell Tower near the State Capitol to play what McCloud called "the what-if game."

The question Robb directed McCloud to begin pondering was what would happen if Robb were elected governor.

Three days before Robb's Nov. 3 election, McCloud gave Robb the results of his effort: a transition plan that filled two volumes and outlined every patronage plum available for Robb's dispersal.

In all, McCloud counted six cabinet secretaries, 121 agency heads, 28 slots in the governor's office, 30 assorted assistants and 1,060 places on boards and commissions. Some were as obscure as the seven-member Virginia Seed Potato Commission but others were as coveted as the State Highway and Transportation Commission.

Most of the state jobs will pay only expenses, but the top administrative positions pay up to $59,000 a year. Robb himself will get $75,000 as governor, an increase of $15,000 over what Gov. John N. Dalton is being paid.

McCloud is now ensconced as Robb's liaison chief, working out of the nearly abandoned state Finance Building, plotting what Robb will do when he takes office Jan. 16. Robb's approach to the job remains as methodical as was his campaign, including the use of a systems analyst borrowed from Reynolds Metals Co. to match up applicants with jobs.

"Chuck insists that the best qualified persons be placed in the jobs," said McCloud. But with the executive branch changing parties for the first time since 1969, politics has not been forgotten. "Being a Democrat isn't viewed as a handicap," is what McCloud tells visitors.

McCloud's two top aides have ties to blocks of voters which were keys to Rob's election, conservatives and blacks. Patricia Perkinson, former secretary of the commonwealth under conservative Gov. Mills E. Godwin, is serving as personnel director for the Robb transition, and Judith Anderson, legislative aide to State Sen. Douglas Wilder, the only black in the Senate, is deputy transition director.

More than 200 resumes have come in unsolicited since the election. They are being filed in gray metal filing cabinets marked, from previous use, "sealed" and "unsealed bids." But the names that are likely to get top priority are those that are hand-carried to McCloud, such as that of a Newport News executive whose name was scribbled on a three-by-five inch card handed McCloud Monday by Del. Alan Diamonstein, one of Robb's closest advisers.

The jockeying for jobs isn't limited to those who want in. High-level appointees in the departing Dalton administration are bailing out -- Secretary of Education Wade Gilley found a haven this week at George Mason University in Fairfax as assistant to the president.

The biggest portion of the transition document -- and according to Robb its most controversial section -- talks about the state's budget and projected revenues. McCloud has been tracking the present budget and tax cuts approved by Congress, because both affect state revenues. He now estimates that Virginia will have $26.5 billion in revenue available in the biennium that begins next July 1, compared to an earlier projection of $30 billion. McCloud said he told Robb, "Once you read that chapter, you won't want to be governor."

Another thick chapter is called, "Promises, Promises, Promises." It details every promise Robb made in the campaign, whether in a position paper or speech, and advises him what needs to be done to carry out the promise: whether he can accomplish his wish by executive order or legislation, and, if so, what are the chances of his promise passing the General Assembly.

Other chapters include an overview of the executive branch; an organizational chart; a guide to personnel selection; a how-to guide to appointments, including a recommended order and timetable for announcements.

The second transition book, entitled "Agency Profiles," provides the governor-elect with a thumbnail sketch of each of the 121 state agencies, including what it does, the name and background of its current chief, size of its staff and budget, and any special requirements. "When Chuck sits down to discuss a particular agency, he'll have three good, tough pages summarizing it," McCloud said.

During the campaign, McCloud, 37, who has worked in state government for 10 years, had very little contact with Robb about progress of his secret transition project. "I'd give him a sketch of it at an occasional dinner, but he was not in a position to focus on it," McCloud said.

McCloud would meet with six advisers on weekends at their homes and discreetly contacted other experts, including Laurin L. Henry, dean of the school of community and public affairs at Virginia Commonwealth University, who as a fellow at Brookings Institution wrote a book on presidential transitions. Henry said part of the advice he gave McCloud was: "Make sure the transition planners link up with the people who are going to hold the power in the administration." It was such a failure in the Carter administration that got it off to such a rocky start, Henry said.

McCloud also contacted the National Governors Conference, the transition chief of Massachusetts Gov. Edward J. King and perused the never-needed plans of three-time Virginia gubernatorial candidate Henry E. Howell.

One of the recommendations, which Robb is in the process of carrying out, was that he meet with all his living predecessors. Robb met yesterday with State Supreme Judge Albertis S. Harrison Jr., who was governor from 1962 to 1966. On Monday, he met with Godwin (1966-70 as a Democrat and 1974-78 as a Republican) and Dalton.

The state provides $40,000 for the transition, plus $10,000 each for the offices of Lt. Gov.-elect Richard M. Davis and Attorney General-elect Gerald Baliles. Although there is not enough money to pay all those needed to assure a smooth transition, the office is partly manned by volunteers who hope to be rewarded with a paying job in the new administration.

So far, no appointments have been announced, although it is presumed that the leaders of the transition team will find a place in Robb's inner office. In addition to McCloud, they include George Stoddard, press secretary, and Laurie Naismith and H. Benson Dendy III, both of whom worked in the lieutenant governor's office before going on leave to take key roles in the campaign.