Dibetta was a standout athlete and one of the most sought-after high school football players in the state in 1963. 
Dibetta signed with LSU following two standout seasons in the Tigers backfield for Coach John Kalbacher. 

He led the state in Class AAA in scoring in 1962 with 120 points (17 TDs/ 18 PATS) and led the state in rushing with 896 yards and was the total offense leader in the local Catholic district with 996 yards.
The 5-10, 170-pound tailback led the Tigers offense to a 7-2-1 record on his way to being named AAA All-State, All-Prep, and All-Catholic League. In a 33-0 win over Nicholls, DiBetta rushed for 116 yards and scored twice. As a team, Holy Cross rushed for 346 yards and 383 in total offense (it's high for the year) in that game.

Dibetta took home MVP honors on the All-District and All-Catholic squads. He was named team MVP and also took home the Johnny Brechtel Memorial Association bronze trophy as the most valuable prep player in the city during the 1962 football season. 
Dibetta was chosen as offensive captain following his senior season for the East Squad in the Louisiana High School Football All-Star game in Baton Rouge. Teammate Dave Dawson was also part of the East squad. 

In his junior year in 1961, Holy Cross posted an 8-2- record and finished second in the district by one game to De La Salle. DiBetta scored four touchdowns but kicked (or ran) for 13 PATs, totaling 37 points. That ranked him No. 4 in N.O. preps. He was the total offense leader in the district and picked on the NO States-Item All-Prep team and named All-Catholic halfback. 

He played quarterback on the 1959 Holy Cross junior varsity team and was an alternate halfback on the 1960 varsity squad. 

In track, Dibetta won first place in the broad jump (21’-1”), placed second in the hop, and step jump, and was a member of the 440-yard first-place relay team in the Junior-Senior track meet. He was also a member of the tiger track team which won the Frosh-Soph Catholic and novice district championships in 1961.

As a senior, he was part of the 880-yard relay team along in addition to his merits in the broad jump and triple jump. Dibetta and teammates Andy Thiel, Glenn Smith, and Charley Chapman established a new Catholic record with a time of 
1:32.8 in the 880-yard relay. 

A product of the NORD program, Dibetta first gained attention in 1957 in both track and football on the 95-pound St. Raphael district champions and city championship team. Was named outstanding back in the Youth Bowl by WWL-TV. Received the B’Nai Brith award as an outstanding athlete in the NORD program in football, basketball, track, and baseball. Was a member of the 1958 All-Star Biddy basketball team which was runner-up to national champions in Wichita, Kansas. 

Upon arriving at LSU, Dibetta was a member of the Tigers freshman team with quarterback Nelson Stokley. He led the frosh team in rushing. One of his highlights came on the opening kickoff vs. Tulane where he scampered 92 yards for a touchdown in a 34-12 LSU win against many of his former teammates and rivals.

Dibetta went on to letter three seasons for the Tigers in 1964-65-66.  
He played tailback as a sophomore, strong back as a junior, and fullback as a senior. 
Dibetta was a permanent captain of the LSU in his senior season of 1966. He won the award for Top Amateur Athlete in the Greater New Orleans area in Nov. ’66 for his performances against Mississippi St. and Tulane. Dibetta won the award twice in high school as well. 

LSU Coach Charley McClendon called him “the most underrated player in the Southeastern Conference” during the 1966 football season. McClendon went on to say “I know no one could represent their high school any better than Gawain for Holy Cross.”