Jimmy Young said yesterday that he would be the next heavyweight champion of the world, and U.S. District Court Judge John Sirica witnessed the vow.

The occasion was a luncheon given at the Touchdown Club yesterday for the 28-year-old Philadephia fighter who considers himself the No. 1 heavyweight contender after losing a close decision to Muhammad Ali at Capital Center, April 30, 1976.

"Ali wants me to fight Ken Norton first," Young said yesterday. "Then, if I beat Norton, I'll get another crack at the title which I thought I really won. I was never so stunned as I was that night at the Capital Center when I heard the unanimous decision for Ali.

"I think I'm the No. 1 contender, not Norton, since beating George Foreman. I'm not forced to fight Norton but maybe I am. I've heard the bout with Norton will be held in September but nobody has told me. I don't want to fight Norton but I'm willing. I mean, it's just another delay to getting another shot at the title."

Sirica had rushed to the luncheon from his court where he had just ordered former Attorney General John Mitchell and former presidential aide H.R. Halderman to begin serving prison terms of from 2 1/2 to eight years.

Sirica said: "This was a sad day for me and for our country to see a man of the stature of the former attorney general of the United States standing before me. It only took me six minutes but it was the toughest six minutes of my life.

Sirica was an outstanding amatuer boxer in his youth.He told Young yesterday: "Nothing takes more out of a man than being in a fight. I never picked a fight but I never ran away from one, either."

Young said he weighs 220 pounds now but expects to trim down to 210 by September, assuming he will fight Norton then. "I've been doing light workouts," he said, "and I'll ready for Norton or Ali. I've been studying Ali ever since he beat Sonny Liston for the title on Feb. 25, 1964. I think Ali still punches well but it is time for him to step aside. I would hate to see him pushed aside. He's a good fighter and still the champion until that somebody takes his title. I think that somebody is me."

Young was reminded that Ali claimed that he was out of shape at 230 pounds in the Young fight. "If that's so." retorted Young, "he should not have fought if he was out of shape. He was supposed to represent himslef as the champion. Norton had three cracks at Ali. I only need one more."