You have asked exactly the right question, and it deserves a direct answer. Was Job depending on his own righteousness or God's through the first 41 chapters? His own. Absolutely. We agree on that completely.
But here is where I think your argument stops short of where the text is taking us.
The man born blind in John chapter nine said something that unlocks the entire book of Job: "Now we know that God heareth not sinners: but if any man be a worshipper of God, and doeth his will, him he heareth." (John 9:31)
That verse is the spine of the book of Job. God does not hear sinners. Therefore every prayer Job offered, every protestation of innocence, every demand for an audience with God through the first 41 chapters — none of it had Melchizedekian weight. Job was praying, but God was not receiving it in the intercessory sense. And then Job 42:8 happens. God turns to Eliphaz and says "my servant Job shall pray for you: for him will I accept." That word accept is doing enormous theological work. It marks the precise moment a sinner becomes a priest. The moment God begins to hear Job is the moment the book has been building toward from page one.
So yes — Job sinned and fell short of the glory of God. But that is not the indictment of Job you are presenting it as. It is the universal human condition that makes the book of Job necessary in the first place.
Consider the company Job keeps in this regard.
Saul of Tarsus was not interceding for others before Damascus — he was dragging them off to prison and holding the coats of those who stoned them. Was that faith? Was that righteousness? By your standard, no. And yet Paul became the man who said "I could wish myself accursed from Christ for my brethren" (Romans 9:3) — the very definition of Melchizedekian intercession.
Peter did not begin as a priest after the order of Melchizedek. He began as a man who looked Jesus in the face and told Him He didn't need to pay the redemptive price for others. Jesus called that satanic (Matthew 16:23). And yet Peter became the man whose shadow healed the sick in the streets of Jerusalem.
James and Jude did not begin as pillars of the church. During the ministry of Jesus they were among those who said He was out of His mind (Mark 3:21, John 7:5). And yet James became the presiding elder of Jerusalem and Jude became a contender for the faith once delivered to the saints.
None of them started as Melchizedekian priests. Every one of them became one.
That word — become — is the word that unlocks Job. The book of Job is not a portrait of a finished priest. It is the constitution of how a priest is made. The suffering, the stripping away of self-righteousness, the whirlwind, the silence before God — these are not the story of a man who failed. They are the curriculum of a man being qualified.
Job 42:5 is the graduation: "I have heard of thee by the hearing of the ear: but now mine eye seeth thee."
And Job 42:8 is the ordination: "him will I accept."
You ask whether Job was clothed in his own righteousness or God's. Through chapter 41, his own — and it was insufficient, which is precisely why God had to strip it away. By chapter 42, God's — which is why God could finally hear him, and why three men's eternal souls were placed in his hands.
The form of godliness was there from chapter one. Job offered sacrifices for his children. He was blameless and upright in his own conduct. But Paul warned Timothy about having the form of godliness while denying the power (2 Timothy 3:5). The power of godliness is the intercessory standing before God that only comes through Christ's righteousness. Job had to lose everything — including his own righteousness — before he could receive it.
That is not a flaw in the typology. That is the typology working exactly as God designed it.
The book of Job is showing us how a man becomes a priest after the order of Melchizedek. They do not start out as one. Neither did Saul. Neither did Peter. Neither did James or Jude. And neither did Job.
I had missed this post. You are saying Job was not saved until the end of the book?