Complex sentence: Giaveno spent along time in the regional Piedmont leagues, and wouldn't gain promotion from the Terza Categoria until the 1980s, they did however record a double promotion, gaining promotion to the Prima Categoria.
Split into simpler sentences: Giaveno spent along time in the regional Piedmont leagues, and wouldn't gain promotion from the Terza Categoria until the 1980s. When it finally came, they did however record a double promotion, gaining promotion to the Prima Categoria.