Eliot Pfanstiehl, director of Strathmore Hall Foundation, the Montgomery County arts center, has a dream. It is that someday the arts center -- now housed entirely in a Georgian mansion overlooking Rockville Pike and the Grosvenor Metro station -- will sprawl over an additional 10 acres and comprise: a large concert hall, a small historical arts museum, gallery space, a grassy mall with extensive landscaping, and a small conservatory.

In essence, says Pfanstiehl, he would like to see Strathmore transformed into a full-blown "artspark." Pfanstiehl presented his plan -- he calls it a "wish list" -- to the Montgomery County Council last month. The foundation is not asking for additional money from the county right now.

"Whoever wants to help us do it, that's fine," says Pfanstiehl, who expects to raise most of the funds privately. It's an ambitious project; the cost estimates range from $13 million to more than $20 million. Musical Resurrections

And now a dream come true: Early music, especially choral music, is undergoing a renaissance among singers and connoisseurs. Michael Harrison, who has sung with the Washington Bach Consort and the American Vocal Ensemble, is so interested in 16th-century choral music that he started his own group, the Palestrina Choir, to present "liturgical music that for one reason or another is no longer performed." The 12-voice group made its debut Saturday night at St. Paul's Episcopal Church on K Street NW.

The Palestrina Choir takes its name from the 16th-century composer Giovanni Pierluigi da Palestrina, who composed chiefly for the Roman Catholic Church. Assembling a group like the Palestrina choir is "something I've been thinking about for years, says Harrison. Harrison hopes to resurrect the music of little known composers like Orlandus Lassus and Josquin des Pre's.

"There is a lot of good stuff out there that never gets performed," he says. The musical scores are not that difficult to find; many are simply gathering dust on shelves or sitting in microfilm canisters. A library at St. Louis University in Missouri contains a microfilm collection of 16th-century Roman church music; the Library of Congress is another repository for choral manuscripts.

"We will be singing all of our music from single voice parts as they did in the 16th century," says Harrison, adding that the choir will also work from early manuscripts that do not contain the bar lines found in modern scores. Harrison says that many times the bar lines put a stress on certain words that was not intended in the original version.

Another concert is planned for late spring, probably featuring a program of works by Palestrina and his predecessors -- "fairly obscure composers that Palestrina seemed to be influenced by." Free Lectures

From our free self-improvement department: The Corcoran School of Art sponsors a lecture by Joel Shapiro at 7 p.m. Thursday, in conjunction with the Corcoran's "Spectrum: The Generic Figure." For information, call 638-3211. Christopher Davis-Roberts will lecture on the Tabwa people of Central Africa, at 7 p.m. March 13 at the National Museum of African Art as part of the museum's exhibition "The Rising of a New Moon: A Century of Tabwa Art." Folk Tales for the Deaf

For the first time, at 8:30 tonight, the National Theatre's "Monday Night at the National Series" will offer an interpretative performance for the deaf. Tonight's program is "The Golden Key Presents Grimms' Folktales in Performance." "This particular production is very conducive" to interpretation by a sign language narrator, says series director Joan Langer. The performance is free; for reservations call 783-3372. Odds and Ends

The Oratorio Society will stage its annual fund-raising auction 8 p.m. Saturday at Alumnae Hall, Trinity College, 125 Michigan Ave. NE. Admission is $5; a "West Side Story" score autographed by Leonard Bernstein, National Symphony tickets and Washington Ballet tickets are among items to be auctioned . . . Sydney Lewis, Hirshhorn chairman of the board, has been elected president of the Virginia Museum of Fine Arts board of trustees; Lewis has been executive vice president of the museum's board since 1983 . . . The deadline for "Currents," the art and history seminar for high school juniors being held this spring, has been extended to March 14. To request an application call 357-3235 . . . Computer nerds rejoice! The National Air and Space Museum, with Digital Equipment Corp.'s help, will open an "Aerospace Computing" gallery in May 1988. Visitors will be able to guide simulated flights with "hands-on" computer consoles . . . Three hundred fifty people spent more than $40,000 at the Corcoran Gallery of Art's annual auction Friday night. William Christenberry, Yvonne Pickering-Carter and Ed McGowan were among the artists who donated works to the auction; proceeds benefit the Corcoran School of Art.