I was worried that searching for the word "dipstick" may have returned a photo of myself
... but you've now put my mind at rest.
As for using a 105 dipstick, that sounds like an idea, but so does MIaGuilia's suggestion of re-marking a maximum level on the 75 dip stick, which I already have.
Also, I'm concerned about overfilling the engine with oil, as this can be as problematic as underfilling it.
Given the significant shape (and possibly volume) difference between the 75 and 105 sump pans, I'm wondering what the best recommended oil volume is for a Twin Spark engine with a 105 sump. How did you arrive at the figure of 6.5 litres?