Robert L. Stuckey, an admitted international heroin courier convicted of 45 criminal charges in connection with his role in a massive scheme to import drugs into Washington, was sentenced in U.S. District Court yesterday to serve a minimum of eight years in prison and pay a $10,000 fine.

During a trial before Chief Judge William B. Bryant last October, Stuckey, 41, testified that the drug ring was lead by convicted tax-evader Linwood Gray. In an earlier, separate trial before Bryant, Gray was acquitted of all charges that he directed the operation, which the government contended imported more than $30 million worth of heroin into Washington. Gray was convicted at that trial of tax evasion involving several hundred thousand dollars over a two-year period.

Before he was sentenced by Bryant yeaterday, Stuckey repeated his defense that he participated in the scheme because he was afraid of Gray.

Assistant U.S. Attorney Robert R. Chapman told Bryant yesterday that Stuckey was the "vice president for overseas operations" and the "chief recruiter" for the heroin operation from July 1976 to January 1979. Chapman also recalled Stuckey's courtroom testimony in connection with the shooting, 13 months ago, of a federal prosecutor who was investigating the heroin ring.

In court papers, the government contended Stuckey made two telephone calls in an attempt to "have the prosecutor ambushed" and later surrendered a .22-caliber pistol to the FBI that was later identified as the weapon used to shoot the prosecutor, who was slightly wounded in the attack.

Chapman said later that no charges have been filed in connection with the shooting, but that the investigation is continuing.

Bryant gave Stuckey seven concurrent sentences in connection with the 45 criminal counts, which included narcotics, foreign travel and passport violations.