Bob Sirois added another plus to his hockey career yesterday when he was selected to play for the Prince of Wales Conference in the National Hockey League All-Star Game at Buffalo on Tuesday.

The 23-year-old winger was chosen as the Washington Capitals' representative by Scotty Bowman, coach of the Stanley Cup champion Montreal Canadians, who will handle the Wales team.

"That's great, I'm really happy," Sirois said when he was informed of the honor. "It's a great feeling just to be dressed with those guys. I'm really surprised. I never thought I was going to make it. Guy; Charron, the Capitals' 1977 all-star) has made a name in the NHL and he has more points than I have. I thought he'd get it."

Although injuries have limited Sirois' effectiveness in the past, he has gained recognition this season as one of the NHL's leaders in plus-minus statistics, a measure of all-round ability computed by matching equal strength goals for and against while a player is on the ice.

Sirois, one the Capitals' two plus players (with Bill Riley) a year ago, is currently plus eight, a remarkable figure on a team with an 8-24-10 record that has yielded 44 more equal strenth goals than it ha scored.

"If I stay even or stay plus, I'm happy about it," sirois said. "I have no goals as far as scoring is concerned. If it get 35 goals, I'll be happy, if I get 5 25 goals I'll happy. All I want to be is a big plus player. That-s the way I grew up with the Junior Canadians and in the American Hockey League. I want to be a two-way player in the National League.

Before he dones an All-Star uniforms, Sirois has four more games with the Capitals all on the road. The ordeal begins tonight in Chicago (WDCA-TV-29 at 8.30 p.m.) and Sirois is looking for a surge to pad the 17-goal total that has been dormant for five games, after he had scored five times in the previous five contests.

"I've always scored goals in stretches," Sirois said. I'll be hot for five or three. If I went 10 or 20 games without scoring, it would really bother me, but five I'm not worried. And if I didn't have any scoring chances, I'd be bothered, but I had good chances against Chicago and the Islanders."

Additionally, one of those fdives goalless games was against Buffalo, a 4-4 tie. It's hard to forget a play early in the first period when the Sabres' brilliant Gil Perreault stickhandled his way around two bewildered Capitals, then was ridden away from the Washington goal by the backchecking Sirois. It was a classic example of what coaches mean they say a palyer goes bith ways.

Sirois is now physically sound, after taking a slap in the leg against the Islanders, a mishap that, along with muscle spasms and a touch of flu, had limited his playing time recently.

In Chicago, the Capitals will be facing a team that whipped them, 3-1, with a 52 shot barrage 10 days ago. The Hawks are undefeated in h heir last four games and boast the best penalty-killing a percentage in the league, a fact that does not help the prospects of Washington's sorry Power Play.

Goalie Gary Smith, who rejoined the Capitals yesterday, was left at home when the team flew to Chicago, last night.