Biaveti should be Biavati!
This non-desmo 250 GP machine was also converted (1962) to desmodromic valve gear.
According to Carlo Perelli in an article in “das Motorrad” the desmomotor was bench-tested
at full throttle for 20 hours without any defect.
Other source: Massimo Clarke In: Super Moto Technica Anno III, n.5 Maggio 1989
We still do not have pictures from the outside and inside (system unknown) of the desmohead.