Actually 7 MZ according to the KTB Admiral Aegean, the 80 is likely an error in the machine-translated copy of La Difesa I am using while not in Italy. MZ 741, 745, 747, 756, 739, 757 and 759.
As you will have seen in the Italian OH the only reference to an attack is from the Sportivo convoy. I have an inquiry out with someone who may know more, but won't know for a few more days. The log of Turbine hasn't survived it seems.
The war diary of Comando Supremo states however that it was the Fassio convoy that was attacked 'repeatedly without results, late 22 August and early morning 23 August'.
All the best
Andreas