"Evita," lyrics by Tim Rice and music by Andrew Lloyd Weber; directed by Harold Prince; designed by Timothy O'Brien and Tazeena Firth; lighting by David Hersey; choreography by Larry Fuller. Produced by Robert Stigwood, David Land, R. Tyler Gatchell, jr. and Peter Neufeld. With Patti LuPone, Mandy Patinkin and Bob Gunton. At the Dorothy Chandler Pavilion, Los Angeles Music Center.

When a play purports to be based on history, should it be obliged to present its history accurately?

Goodness, no. Just imagine a theater piled high with such lackadaisically lifelike fare as "Sunrise at Campobello" and purged of such inspired fantasties as "Mac Bird" (or, for that matter, "Macbeth").

But if accuracy is asking a bit much, aren't we at least entitled to expect that history, when used at all, be sharply examined and vividly portrayed? This is a test that "Evita," underneath the ingenious direction of Harold Prince and the striking score by Andrew Lloyd Weber and Tim Rice, fails miserably. It casts a dazzling light in virtually every direction except that of its subject, the career of the revered first lady of postwar Argentina, Eva Peron.

Still a hit in London, where it originated, "Evita" begins inside a Buenos Aires movie theater in 1952. A pompous Pampas melodrama is interrupted by the announcement of Eva's death (of cancer, at the lengend-enhancing age of 33).

A nation is plunged into weeping. And when Harold Prince is in charge of things, "a nation" means a nation. "Evita" is packed full of electric pageantry. When Peronism triumphs at the end of Act I, it does so in a spectacular, goose-stepping tableau of banners and torches. Other directors find it hard to fill stages as colossal as that of Los Angeles' Dorothy Chandler Pavilion; but with "Evita" and "Sweeney Tood," now at the equally cavernous Uris Theater in New York, Prince demonstrates that no hall is too big for his big ideas.

There are small delights as well. Juan Peron's emergence as the key power among all the other nationalistic generals is played as a game of muscial chairs. Eva's carnal voyage through a succession of ever-classier lovers is pantomimed in a number called "Good Night and Thank You," which has her bemoaning, to each male discard: "Oh, but its sad when a love affair dies."

"Evita" has dialogue, which presumably makes it an "opera" rather than a "musical comedy" according to the odd system of classification used for such enterprises. But it is handsomely illustrated with film footage of the real Eva, and cynically narrated by a bearded, khaki-suited, somewhat wimpy young man identified as Che Guevara. As played by Mandy Patinkin, this Che may offend some with exalted, macho visions of the late guerrilla proselytizer, but Patinkin gives a sympathetic, consistent and rather sweet performance.

The real Che was a medical student in Argentina during Eva's last years in power, and not conspicuously involved in his own nation's politics. But years later, after his annointment as a continent-wide revolutionary coordinator, he found it useful to work with the remnants of Eva's leftist supporters -- the legions of radical unionists who believed she had devoted herself selflessly to their interests.

[In the end, however, they proved unresponsive to the ramshackle guerrilla movement founded, with Havana's support, by one of Che's colleagues. This Argentine revolution was crushed before it ever got off the ground and the Peronists, whom Che had seen as potential revolutionaries, eventually brought back the corrupt and feeble exile, Juan Peron, for a second try at government in 1973, complete with a new wife whom he vainly tried to make into another Eva. Isabel Peron briefly succeeded her husband as president, but never exerted as much power in office as Eva had exerted with no office].

The Che of "Evita," buzzing over the story like a mosquito, seems to promise an ideal perspective for delving into the mystery of why a nation would throw itself at the feet of so transparently vain, ignorant and dishonest a woman. Eva Peron had used her body to obtain power, and she used her power to persecute and humilitate the objects of her petty grievances. She also managed to buy $40,000 worth of Paris dresses a year and to salt away about $20 million in Swiss bank accounts.

But as the show unfolds, Che seems content to document the undeniable truth that Eva Person was a fraud -- which is only half the story. She was a fraud, but a fraud whose genuine hatred for the rich shined through in her speeches, who gave Argentine women the vote, who raised workers' salaries at the expense of corporate profits, and who took great delight in managing a vast national charity for the benefit of supplicants who brought their problems to her directly. From Juan's first inauguration in 1946 until her final months of life, the whole Argentine government was at Eva's fingertips.

All this, however, is given short shrift or none by "Evita" [as is, more justifiably, the 20-year disappearance of her corpse, which Eva had hoped to have perfectly embalmed and displayed after the fashion of Lenin and the Pharaohs].

As Eva, Patti Lupone must deal with the shallowness of both the character and the authors. It is a losing battle. And since her singing voice is hard to understand in certain registers, her performance comes across, perhaps unfairly, as one of "Evita's" serious drawbacks. Nonetheless, Lupone rises splendidly to the occasion of "Don't Cry for Me, Argentina," an exttremely evocative musical transliteration of her appeal.

"Don't Cry for Me, Argentina" is the high point of an exiciting score that palpitates between Latin and English rock rhythms. To judge from a comparison with the British record album, the score has been slightly de-rocked for its U.S. presentation, and it seems more thematically consistent and more forceful as a result.

When "Evita" reaches Broadway in the fall, it will join "Sweeney Todd" to form a small revolution in the shape of the American musical. For all the physical and musical splendor of both shows, neither is very clear of purpose. But that should not diminish their value as pace-setters. Revolutions, even the best of them, take time to show their true worth.