BY THE TIME he's ready to play Saturday night, Michael Keir might be exhausted from shaking his head back and forth.

Keir, a 6-2, 215-pound quarterback from Roman Catholic High, remains bothered and bewildered, even disgusted, by the fact only 28 players will represent Non-Public vs. Public - the roster limit is 50 per team - in the 39th annual City All-Star Football Classic, set for 7 o'clock at Northeast High.

"Twenty-eight? That might be generous," Keir said yesterday. "Since they counted up that many, I'd bet we've lost a few more. Some guys came out for one or two practices, and I haven't seen them since.

"I don't get it. This is for bragging rights. Your last football game as a high school senior. I can't wait. I'm so itchin' to play."

Keir is so pumped, in fact, he dropped this bombshell:

"I wish I didn't have my prom Friday night."

Wow, here's hoping his girlfriend, Chelsea Keenan, a senior at Palumbo (kids from that school play their football for Horace Furness), doesn't read the good, ol' People Paper.

Wait. There's more . . . But this part is good.

"Next week, we'll be going to her prom," Keir added. "And then we'll be going down the shore."

Amazingly, Keir, whose passing wizardry produced 4,744 career yards and 37 touchdowns, and who's bound for Division II California (Pa.), is the only Roman player in the game.

Some fellow Cahillites, he said, nixed playing because they've made arrangements for post-prom jaunts to the shore or Poconos. Others, according to Roman coach Joe McCourt, were extra dedicated to a spring sport and did not want to multitask. Star receiver William Fuller, a Notre Dame commit, politely declined the invitation.

"I thought Chris Cruz and J.J. Logan were going to be with me," Keir said. "Instead, they just decided it wasn't something they wanted to do.

"I'm definitely missing having Will out here. Playing with him for 3 years was a real treat."

The Non-Pub is experiencing its numbers miseries, in part, because it draws from so few schools, compared with the Pub. Also harmful is the fact Penn Charter's senior prom is Saturday night; no Quakers are playing.

West Catholic coach Brian Fluck, the game's president, said a new rule is being discussed. Players from Catholic League schools in the suburbs would be given the chance to play in this game or in the one involving players from their respective counties.

"It's not definite yet," Fluck said. "But we think it would be good. We think guys would like playing on the same team with guys they've always gone against."

Said Keir: "I guess it's good, in one way, that our numbers are low, because each guy will get more playing time. But there's that risk of getting tired, because the quarters are 15 minutes. We'll need to score points, but it would be nice to control the ball, too."

Is there any chance Keir will see playing time on defense?

"No way," he said, laughing. "I am filling another role, though - long-snapper. I haven't done that since my freshman year, when I was the backup QB and long-snapper."

In practices, in assorted sets, Keir and his big arm have bonded with wideouts Max Pascavitch (Father Judge) and Bobby Keyes (Springside Chestnut Hill Academy) and tight end/handyman Sharif Custis (Neumann-Goretti).

"It's going the best with Max," Keir said. "We've had a nice chemistry from the start. I like throwing to him. I like how he runs his routes, and how he goes about everything."

Along the way this school year, Keir, who lives near 29th and Tasker, received interest from several Division I schools. He needed a few more points on his SAT, however, and there were times when he considered spending a year at a prep school.

California (Pa.) offered a full ride, however, and indicated he should be able to challenge for playing time as a freshman.

Dotted line, meet his signature.

Once the All-Star Classic drew closer, Keir figured he'd better call his future college coaches and ask whether they'd support his participation.

"They told me to go for it," Keir said. "They said a high school senior should have as much fun as possible."

What a concept!