Just a thought hamfoh -

Couldn't you take one of your current bikes that fits you well and do:
[current ST] + [current seatpost] - [dodici seat tube] = [length seatpost needed on dodici]

If you're gonna need some 300mm seatpost then look at the next size up.

I'd assume if you had a very different seat tube angle between the two bikes that might make your results moot.