Sorry, but it is a worthless test because the Breastplate is made with modern materials by modern methods…
(and modern steel is not automatically better at stopping an arrow then armour back then… some modern steel is too brittle)
The armor vs longbow debate is so problematic because there are so many factors and unknown.
Material and production method of arrow
Material and production method of armour
Thickness of armour
Type of armour (a breastplate can be made in many ways)
Range
Angle of impact
Strenght of bow
Velocity
etc…