George Allen reached an agreement in principle with Montreal Alouettes' owner Nelson Skalbania today to purchase the Canadian Football League team. The sale, reportedly for $2.8 million, is contingent upon Skalbania's settling several large debts incurred by the team last season.

"We've moved another five yards," Allen, a former coach of the Washington Redskins, said after a meeting with attorneys representing both sides. Allen also said Skalbania has until next Wednesday to complete significant details of the agreement but indicated the team's troubles were on the way to resolution.

Allen, the team's president and chief operating officer since February, and Bill Harris, a California businessman and Allen's primary financial backer, met with attorneys today to work out some of the snarled details surrounding the Alouettes' ownership situation.

In a three-paragraph statement released after the meeting, Allen said he had been "assured and expects that all past differences have been resolved, and that by next Wednesday, significant details of our agreement will have been completed by Skalbania."

Neither Skalbania, who left Montreal early Tuesday evening, nor Harry Ornest, his appointed stand-in team governor, attended the session with Harris and Allen. Neither was available for comment.

Harris was openly optimistic about the progress on purchase of the team.

"We have finalized things with our lawyers today," he said. "And everything is, truly, in the hands of the attorneys over the next few days. But it looks as if we can finalize this whole thing."

Harris said he and Allen would be meeting with some Montreal-area investors, but declined to identify them, saying, "Most of our investors want to stay anonymous at this point." Harris indicated there are some American investors as well.

Allen said former Alouette owner Sam Berger would join the new owners as a minor shareholder.

Berger, Alouette owner from 1970 to 1980 after owning the Ottawa Rough Riders in the 1960s, said he was informed after today's meeting that Skalbania had agreed to produce signed waivers from the team's creditors absolving the new owners of debts run up during Skalbania's disastrous one-year ownership.

"The problem was that new debts kept surfacing all the time," said Berger. "They want Skalbania to clean them up; to come back in a few days (next Wednesday) and say, 'Here it all is,' and they can go ahead and buy the team."

Allen was more visibly optimistic today, but would not discuss any details of the Alouettes' situation, saying only, "We're making progress."

His son, George F. Allen, one of the attorneys involved, added, "The ball's in Nelson's (Skalbania) hands now."

Since the senior Allen joined the team in February, he and Harris have tried to exercise an option to buy 51 percent of the Alouettes before the end of 1982.

However, the recent presence of Ornest, to whom Skalbania reportedly owes $1.6 million, fueled rumors that Skalbania would turn his controlling ownership over to Ornest, and that Allen would resign.

Harris and Allen have spent most of this week huddling with the current owner and attorneys, hoping to clarify the situation and take over the club.

Although the team's 1981 season debts total perhaps $1.5 million, Skalbania got involved several persons who, according to a club spokesman, "thought they were buying a piece of the team, when all they really bought was a piece of paper saying Nelson owed them money."

After Allen made his noontime statement at a downtown hotel, he and his son went to the Alouettes' offices. A hotel doorman asked Allen, "Have you decided if you want a taxi or limo?"

Allen, a bit closer to becoming a budget-conscious owner, said, "No, we'll take the subway instead."