THE W. C. and A. N. Miller Development Co. is planning to build a complex with about 300 houses and a four-story office building on a 43 1/2-acre site bounded by 49th Street, Dalecarlia Parkway and Massachusetts Avenue NW, one of the largest undeveloped sites in the city.

The company will seek District approval of the plan soon, a spokesman said, and hopes to develop the site over the next 15 years. The neighborhood, Spring Valley, has long been considered one of the prime areas of the ciy.

Michael Seay, sales manager for the Miller firm, said that the Spring Valley complex would include 37 detached houses, 198 semi-detached houses and 72 town houses. Miller is asing for rezoning of a site at Massachusetts and Yuma Street NW, where it wants to build the large, four-story brick office and commercial building.

That building, designed by architect Eugene Delmar, would have 86,000 square feet of office space and 70,000 square feet of commercial space, with both grade and underground parking. A supermarket is expected to be one of the first-floor tenants, the Miller firm says.

The company, developer of Spring Valley and the nearby Wesley Heights neighborhood, is completing a group of 35 houses on a block northwest of the proposed development. Prices of those nearby new houses originally started at $239,000 and now range to nearly $300,000.

A brook runs through the undeveloped Spring Valley site, which the Miller firm has owned for many years. Seay said Miller abandoned plans to build apartments there in the 1960s. George Denby, current president of the Spring Valley Citizens Association, said there was neighborhood opposition to that proposal.

Denby said his association has asked an architect to review the latest Miller plan, which he said looks "reasonable to me at this point."

Residents of that part of Northwest unsuccessfully fought the construction of a high-rise office building next to the Spring Valley Shopping Center, saying it would overwhelm the low-rise area around it. That building currently is being completed on the former site of the Apex theater.

Robert Benson, vice president for finance of the Miller firm, said that an application for a planned unit developemnt on the 43 acres will be sought next week. Such an application would allow for flexibility in developing the site and would transfer commercial zoning for two acres on 49th Street to a corner of Massachusetts Avenue, "just around the corner. We have notified neighbors and the citizen and neighborhood organizations, and so far, the reaction has been good."