@oralloy,
I still maintain that translating Hebrew doctrine from Hebrew sources to be more precise that translating them from a Greek translation.
Even with the changes the Masoretic Hebrew scribes may or may not have introduced, there would not be the language impediment associated with translating it from the Greek.
Also, simply because the New Testament writers quoted the Septuagint does not prove the Septuagint's verity over the Masoretic texts.
Contradictions should be taken in light of one another.
Here is an example where the Septuagint is clearly wrong.
Were Mary and Joseph Married or Engaged at Jesus’ Birth?
https://www.biblicalarchaeology.org/daily/biblical-topics/bible-interpretation/were-mary-and-joseph-married-or-engaged-at-jesus-birth/
The Septuagint has Mary and Joseph engaged when they traveled to Bethlehem but the were fully married.
Contrarily, it was a virgin conception but not necessarily a virgin birth.
What kind of man would not consummate a marriage after marriage was final, baby on the way or not?
The angel told Joseph to "take Mary as his wife". It is quite evident what that means...
Joseph also took Mary to pay their taxes while she was pregnant.
Now, this is why many reject the Masoretic texts over the Septuagint because they prefer Mary being a virgin not only at Jesus' conception but at Jesus' birth also...
Is this the vital differences you refer to?
This is one "difference" that the Masoretic texts seem to clearly win out over the Septuagint.
Almah (עַלְמָה 'almāh, plural: עֲלָמוֹת 'ălāmōṯ), from a root implying the vigour of puberty, is a Hebrew word for a young woman of childbearing age. Despite its importance to the account of the virgin birth of Jesus in the gospel of Matthew, scholars agree that it has nothing to do with virginity.
Wikipedia
The Septuagint translates the word for, "a young woman of childbearing age" and instead substitutes the word virgin.
This is probably your only reasoning for using the Septuagint... lol
People carry this even further and call Mary, "the perpetual virgin". The New Testament is very clear that Jesus had siblings...