Is it allowed to overtake in the mentioned situation?

Explanation

The broken centre line may be crossed, and the triangular 7% sign only warns that the road climbs; neither feature creates an overtaking prohibition. Seeing far enough ahead and being able to complete a pass safely are general duties on every road, not an additional condition imposed by this gradient sign. Treating that universal duty as a special restriction here misdescribes why the manoeuvre is permitted.