There was a gtv I saw that was Ferrari yellow, looked nice. But I think adding a slight pearl to a period color, since you like yellow I'd recommend: AR-109 Giallo Ocra - Ochre (also Autumn Gold) I like the darker blue: Blu Olandese (AR-343); darker red: Rosso Amaranto (AR-509). But those are all from the 70's, with the 80's the Alfa paint code site
ALFA ROMEO PAINT CODES shows: Alfa Yellow Met.(AR-137) as being used in '82, but I couldn't find a picture of it, but the Spider might be close.