Democratic gubernatorial candidate Andrew P. Miller wound up a two-day tour of Virginia's heartland today, advocating policies and courting political figures that have sustained conservative officeholders of both parties here for decades.

In rural Southside counties near the North Carolina border yesterday, Miller opposed any increase in the state tobacco tax, among the lowest in the nation, promised to preserve the state highway trust fund for road contruction only and said he would oppose any proposals to give an excutive agency authority to transfer water resources from one region of Virginia to another.

The sanctity of the road fund, fed by a 9-cent-per-gallon tax on gasoline, and opposition to taxes on tobacco, a major source of agricultural and manufacturing wealth in the state, have been staple policies of conservative government that has dominated Virginia in modern times.

Water is a new issue created by fears of future shortages in the metropolitan areas of Northern Virginia and Hampton Roads. However, Miller's water policy statements fit a pattern of assuring rural areas that their interests will not be sacrificed by a centralized government to the needs of growing cities.

When he came to this Shenandoah Valley city today, Miller was greeted by R. R. Smith, chairman of Smith's Transfer Corp., a trucking company. Smith has contributed $10,000 to the Miller campaign and the candidate today flew to Staunton from Richmond in the corporation's executive airplane.

Miller stated his opposition yesterdaay to paying the $35 million annual cost of the State Police Force from the state's highway fund, thus reducing the money available for roads. He said the reason for his stand is the need to maintain rural secondary roads. This policy, however, also fins favor with the trucking industry, which has supplied about 10 per cent of the financing for Miller's record primary.

Road builders also are concerned about highway construction spending and Miller has attracted their support. Throughout yesterday's tour of Southside, Miller flew in a plane contributed by the J Lawson Jonws Construction Co. of Clarksville, a major builder of highway bridges.

In addition to taking positions sure to find favor in the conservative belt from the state's south central border through Richmond to the Shenandoah Valley, Miller also collected the blessings of some of its better known conservative political figures.

In Halifax County yesterday former Gov. William M. Tuck, a vigorous foe of racial integration and large federal government. was among those who greeted Miller at the Tuck Airport in South Boston. In Richmond today Sen. Edward E. Willey (D-Richmond), president pro tem of the Senate, endorsed Miller at a joint press conference. Willey was a loyal member of the old Byrd organization in its latter days. He has continued to support Sen. Harry S. Bryd Jr. in his races as an independent against Democratic opposition. He also is a firm backer of Gov. Mills E. Godwin, a former Byrd Democrat who became a Republican in 1973.

Willey was deposed as Democratic leader of the Senate in 1976 by a coalition of moderate conservative Democrats led by Sen. Adelard L. Brault (D-Fairfax), majority leader of the Senate.

After today's press conference, Miller said in an interview that he expects to include Willey in his program planning. "I expect to avoid the kind of conflicts with the Assembley that lead to vetos by sitting down with leaders like Ed Willey and Abe Brault to work out a program we can agree on," Miller said in answer to a question.

Brault is among the five (of seven) Democratis senators in Northern Virginia who have endorsed Miller.

Miller, exlaining his opposition to a tobacco tax increase said this policy is consistent with his opposition to all "discriminatory taxes." He included in these a state tax on the value of coal as it is mined. Such a coal severance tax proposal was defeated in the Virginia Assembly in 1976. Miller and Howell both strongly oppased it at that time.

The coal industry has contributed heavily to both the Millerand Howell campaigns during this primary. Howell has received about $50,000 in contributions from coal operators*or industry sources and Miller more than $150,000.

The Miller campaign has sought successfully to draw back into the Democratic Party such conservative leaders as Willey and Tuck who deserted it during the last 10 years to support Republican presidential candidates and statewide office seekers opposed by Howell and his more liberal followers in the party.

However, Miller sees his conservative support only as a part of a board coalition that he is trying to build. He has sought the support of black Virginians even though Howell is presumed to be their favorite in this race.

At South Boston yesterday, the crowd greeting Miller included a substantial number of blacks.

In an interview today Miller said he sees no conflict in trying to unite conservative and liberal Democrats behind his campaign.

"Those who are more liberal are most concerned with the nature of the state response to such needs as programs for handicapped children.

"The goal of my administration is to come up with the best response possible within the state's fiscal resources and to make sure that our response is carried out with competent management."

Miller's stress on competent management and the natural contrast between him and Howell, who has made consumer advocacy a central feature of his political career, has attracted overwhelming business support to Miller.

"There is no comparison in the qualification between Mr. Miller and Mr. Howell," trucking executive Smith said. "The way Henry Howell talks scares me to death."