He went 1-1 at 147lbs with Hans-Henrik Palm in 1975 and 1976 (avenging defeat before turning pro), at the Danish championships. Before that, he was African champion at 139lbs in 1973 (having always done well in the juniors in the early 70's) but lost 4-1 to Aaron Pryor at 132lbs at a multi-nations meet in 1973 in what was said to be a real close fight. He won the 1974 commonwealth games at 132lbs, representing Africa, and then won the 1974 world championships at 139lbs, again representing Africa.
In the pro's, Sugar Ray Leonard described Kalule as his most difficult ever win. He was beating Mike McCallum before the stoppage, and was the last guy to beat Sumbu Kalambay before the Nunn KO.
Good fighter ;) One of the best southpaws ever I'd say, amateur or pro.