My guess, for a good tech with proper equipment and experience, would be 20 hours. Maybe less.
Problem is experience. Not a routine job that many techs outside a race team would do more than once or twice on an MV model. Yam-Suz-Hon-Kaw might be different experience level (lots more of them out there and getting rebuilt).
Flat rate for most Jap in-line 4 sport bike crankcase R&R is around 10 to 20 hours.
Figure if he/she takes their time, measures everything carefully, cleans everything perfectly, torques everything correctly and has done it before....20 hours. More if it's the first try.