No, its not a direct replacement, the EV was single phase, you are saying the Ducati is a 3 phase.
It might work but at $600 its an expensive try. BTW the original is Ducati Energia, no relation to Ducati motorcycles.
The problem with the original Ducati Energia regulator system is the Voltage referent circuit is very flakey. If you just replace the original regulator with a direct connected one the charging will be more reliable.
The original wiring relies on a couple of bullet connectors in the yellow wires from Stator to regulator, they often develop resistance and burn up, re-connect those with crimp links or soldered joints for reliability. Perhaps replace the wires right at the coils, its easy to solder new ones on there, the old ones will be oxidized and almost impossible to re-solder.
Here's a typical https://www.electrosport.com/collections/street-motorcycles-moto-guzzi-2001-california-ev
Its Plug and play but I would recommend changing the wiring slightly to fix the bike's flakey Voltage reference.
The regulator Electrosport recommend is not one I would chose, they used to have a better one with a dedicated Negative wire, the ESR515 needs to be grounded.