"We open in Missoula, then on to Great Falls" could be the fitting variation on Cole Porter's "Kiss Me, Kate" song for a professional acting company in Montana.

A professional acting company in Montana? A state with less than a million population and half of that living in communities of less than 3,000?

As Walter and Page Stegner point out in the current Atlantic, the Rocky Mountain states, "suburbs of Eden," may "profoundly affect the future of the whole country." Their vastness holds a huge share of the nation's remaining mineral wealth.

The creation this year of the professional Montana Repertory Theater, following the birth last year of the Alaska Repertory Theater, is a stimulating reflection of what's going on with the performing arts in the nation. More important, such a theater in what previously had been an unlikely area for theater, can forecast what might be by 1988.

The Montana Rep. with five Equity actors, two directors a stage manager and a technical staff of four, began in February with two plays in repertory for a three-month season of rehearsals and performances. Admittedly, it's modest. But it's also proud - proud and heady the way pioneers are - that this winter has been a start.

It also reflects the increasing liaison between professional and university theater.

James D. Kriley, the thirtish, tall and burly managing director of the company, also is chairman of the drama and dance department of the University of Montana. He was in town last week for the American College Theater Festival and only too pleased to answer such questions as: "How come Montana has a professional theater company?"

"This really goes back more than 10 years," says Kriley. "The university had a long-standing student program, and once or twice a year, with help from the Montana Arts Council, touring began within the state but always, the aim was to achieve a professional company.

"Don't forget, too," Kriley adds, "we're not the first pioneers. In this, the 'Treasure State,' companies traveled plays to the miners and small settlements. We're not hicks back here in Montana."

That "we" and "here in Montana" is deceptive. The interviewer had known him first as a member of the Emporia Kansas State University with a Ph. D. from Utah.Born in Seattle, Kriley and his wife, Mary, who also comes from Seattle, had seemed settled for good in appreciative Emporia.

Kriley continues: "Yes, there is a great pioneering feel to all this. It truly is 'Big Sky' country: the mountains, the great spaces. Someone said recently that Montana is the kind of state where commuter planes are a commonplace.

"How did we get started? We built on what existed, aware that the state has less than a million people and that since half of them live in small communities, we'd have to tour to serve.

"With advice from FEDAPT (the Foundation for Extension and Development of American Professional Theater, based in New York), we created a theater-in-the-schools program which presented 420 workshops all around the state last fall. That workship program is basic to our work and brought us a $10,000 expansion grant from the National Endowment for the Arts.

"Our university president, Richard C. Bowers, has been imaginatively supportive, giving us the university facilities and $15,000 in cash to float our first moves into professionalism. In New York, Los Angeles and Seattle, the latter a coming theater base with five Equity companies now, we auditioned over 700 adventurous wanting-to-work actors.

"For our first two plays in repertory we chose Neil Simon and Eugene O'Neill, 'playing it safe,' someone claimed. Maybe Simon's 'The Good Doctor' seemed like playing it safe, but you know what? O'Neill's 'A Moon for the Misbegotten' outsold Simon.

"We opened in Missoula for two weeks, then played Great Falls, Chester, Kalispell, Polson, Helena, Butte, White Sulphur Springs, Sidney, Wolf Point, Miles City, Forsyth and Billings. Bet you've only heard of about three of them. One has only 300 residents but came up with $2,000 for us to give the two plays in two nights.

"We located interested people in all those place and gave them budgets of what our time would cost. For one performance it's $1,000, for a performance and a day in the schools or with a community group, it's $1,500. We go up to $3,500 for four days with the schools or groups plus three evening performances.

"Six towns chose two plays and many single-play towns took O'Neill over simon, which suprised us. Tougher to perform, O'Neill's power gripped our audiences.

"For the schools we do our workshops adapted to various grade levels. For the community groups we have our Plays-for-the-Living program. THese are short original plays written specifically to evoke discussion on family and community issues, dealing with alcoholism, aging, death and parent/child relationships. This has become a provocative series for audiences and performers both, a give and take across the audience-performer gulf and we plan to continue the scheme.

"What we've discovered is intense curiosity and the notion that TV works both ways. The good things on TV have made people aware of what's available and the bad things on TV have made people impatient about how they'll spend their time. TV is both positive and negative to us all. Live theater is an alternative and we're prepared to make people chose the alternative. If what we offer is good enough, that's the way it will roll."