I don't think that to trust the Holy Bible to be the pure Holy Bible hinges upon the truth or facts of the LXX alone.
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Having said that,it is assumed that to use as regular,the tainted LXX for the foundation would not be good.
Having said that, this does not mean that all tainted MSS are of no value.
There are many good and legitimate readings in almost any MSS or Papri out there.
Having said that,any usage by an KJBer ,however tiny, does not legitimize the whole of it.

Holy Bible
There is only one.