Again, the 'supposed text of the Septuagint' is taken from the Alexandrian Texts or Manuscripts. The Alexandrian Texts are made up of 45 manuscripts. Three of these are of major influence. They contain both Old and New Testament in Greek.
1.) Codex Sinaiticus
2.) Codex Vaticanus
3.) Codex Alexandrinus
These are dated 4th and 5th century A.D. Not 3rd or 4th century B.C. There is no evidence that there was any such Septuagint in 3rd or 4th century B.C. as is claimed. Other than the proven lie of it's origin in 'Letter of Aristeas'.
Origen's translation of the Bible is dated at 200 A.D. It is called the Hexapla. Because Origen's translation of the Old Testament agrees with the so called Septuagint, found in the Alexandrian manuscripts, it is claimed by some that he actually was copying or translating from the Septuagint. But all that can really be claimed here is that the Alexandrian manuscripts agree with Origen. Not that Origen translated or copied from any Septuagint.
And, as I have already noted, it is known that at the end of codex Vaticanus, it says it came from Origen's Hexapla. In other words, these earliest Alexandrian manuscripts are really Origen's translation. Not any so called Septuagint written in 3rd or 4th century B.C. So, when it is said a certain quote comes from the Septuagint, what it is really saying is that it is from Origen or the Alexandrian Text.
So, because Westcott/Hort used almost exclusively the Alexandrian Texts in their translation of the New Testament, then their Old Testament quotes naturally agreed with the so called Septuagint found in the Alexandrian manuscripts. And naturally agrees with Origen.
Quantrill