Like the Australian period films that preceded it, notably "My Brilliant Career" and "The Getting of Wisdom," the new Australian import "We of the Never Never" evidently turned to a work of autobiographical fiction published around the turn of the century.

The heroine is the author, Jeannie Gunn, recalling the savory and bitter experiences of her first year of marriage to Aeneas, who after several sedate years as a Melbourne librarian, leaves to manage a remote cattle station in the Northern Territory of Australia.

Having accepted the job, Aeneas defies the conventions of 1902 and takes his adventurous bride with him into a harshly exotic, beautiful wilderness. Melbourne is left several weeks away by boat, train and horseback by the time the Gunns arrive at their first home, a spacious but unfurnished, ramshackle barn euphemistically misrepresented as "a commodious station homestead." Jeannie claims the dubious distinction of being the first white woman to intrude on this sparsely populated region--"never-never" land--occupied by a handful of white stockmen and the scattered aborigine communities that have attached themselves to the cattle stations, trading intermittent labor for grudging rations of flour, sugar, tobacco and hand-me-down clothes.

The appealing aspects of this unconventional honeymoon keep the movie pictorially impressive and dramatically promising for better than one hour. In fact, "We of the Never Never" shows every indication of evolving into a more authentic variation on "The Man from Snowy River."

In "Never, Never," we have an account of ranching life in a territory still far beyond the reach of civilized comforts, complicated by the heroic effort needed to sustain a new marriage in far from hospitable surroundings. The early sequences, which depict the Gunns' arduous journey to the outpost, their successful passing of tests designed to separate the tenderfoots from the survivors and their general settling in , are vivid and stirring.

The story structure is obviously episodic, but you feel the episodes are adding up to a comprehensive, affecting impression of a unique experience and way of life. Moreover, the Gunns are played by such gauntly unglamorous but potentially touching and authentic actors-Angela Punch McGregor as Jeannie and Arthur Dignam as Aeneas--that the love story promises something out of the ordinary. McGregor and Dignam are best known here for fine performances in Fred Schepisi's Australian films; she playing the pathetic little wife of the title character in "The Chant of Jimmy Blacksmith" and he as the sternly frustrated young priest in "The Devil's Playground," who dreamed of being submerged amid a throng of naked beauties. An almost comically angular match, they nevertheless seem right as an idealistic and devoted Edwardian couple.

I don't know if the slowly emerging but ultimately lethal dramatic defects in the scenario derive from fidelity to the source, but something certainly stops "We of the Never Never" in its tracks for about the last 45 minutes..

The insurmountable problem is that the story degenerates into an extended death watch. Everyone waits around with long faces while three characters in succession succumb to a mysterious bush fever, which evidently takes its victims quietly but inexorably. This is not the best of all conceivable developments for the story of pioneering life we seemed to be watching in the first hour. The error may be misplaced fidelity to Jeannie Gunn's memoir, but something goes irreparably haywire from the storytelling standpoint.

If the funereal mood that stifles the concluding section of the movie isn't a blunder, then the upbeat expository material was faulty, because it neglected to prepare the audience adequately for such a drastic turn. A problem of modulation, I suppose, but the appropriate modulation eludes director Igor Auzins and writer Peter Schreck by a margin wide enough to transform an initially winning movie into a stupefying ordeal. WE OF THE NEVER NEVER

Directed by Igor Auzins; written by Peter Schreck; edited by Clifford Hayes; produced by Greg Tepper; executive producer, Phillip Adams. A Columbia Pictures release. This film is rated G and runs 133 minutes. THE CAST Jeannie Gunn. . . . Angela Punch McGregor Aeneas Gunn. . . . Arthur Dignam . . . . Goggle Eye. . . . Donald Blitner . . . . Bett Bett. . . . Sabina Willy