The broken heads are unfortunately a very common and of difficult solution trouble in Bows. For this reason a Bow repaired in the head undergoes a very serious devaluation and I always recommend, before acquiring an expensive old Bow, to conduct an x-ray of the head. This is also one of the most uncertain work about duration.
When possible, as in this case, after gluing the head in the right position, I insert a not passing carbon pin and cover it with a pernambuco plate.
In this case the result was excellent and almost invisible.