I have also found what purports to be a 'literal translation' of 53:4-6 by a guy called Otfried Hofius ('The Fourth Servant Song in the New Testament Letters). Interestingly, Hofius is something of a liberal and he hates the idea of penal substitution, but he finds he cannot deny its existence in these verses. The italics show where an emphatic personal pronoun occurs in the Hebrew:
'Surely our sicknesses - He bore them,
and our pains - He suffered them.
Yet we considered Him as one stricken,
as one struck down by God and afflicted.
But He was pierced for our transgressions,
and crushed for our iniquities.
The punishment for our salvation lay upon Him,
and by His wounds, healing came to us.
We all have strayed like sheep,
each of us has turned to his own way;
but Yahweh has caused to fall on Him the iniquity of us all.'
Emphatic personal pronouns are also found in verse 11 -
their iniquities - He will bear them,' and in v.12 -
'For He - the sins of many, He bore them.' All of this serves to underline the simple fact that the Servant, who is distinct from God's people, suffered in their place, as their substitute.
I looked up the words 'chasten' and 'chastise' in the
Oxford Concise Dictionary:
Chasten: 'Discipline, punish by inflicting suffering, moderate, restrain, subdue.'
Chastise: 'Punish, thrash.'
'You have been found guilty of the most heinous crimes. You will be taken from prison to a place of execution and there you will be hanged by the neck until you are dead - but it's not a punishment, so that's OK.'

The meaning of those verses is so staringly obvious that I think you have proved the case for me.
Our transgressions demanded wounding:
He was wounded instead of us.
Our iniquities demanded crushing:
He was crushed instead of us.
The only way we could get peace with God was through His chastisement:
He bore that chastisement.
The only way we could get healing was through His wounding:
He received that wounding instead of us.
He was cut off from the land of the living instead of us.
Our transgressions merited being stricken:
He was stricken instead of us.