Take a look at this genealogy comparison chart of Genesis below. It compares the birth,death,life span of the Masoretic text, the Samaritan Pentateuch and the Greek Septuagint.
If the two witness rule is to be applied, then the Masoretic text is wrong with the first born data of Arphaxad, Salah, Eber, Peleg, Reu and Serug. The Greek Septuagint and Samaritan Pentateuch both agree when these first born sons appeared in the timeline. For some reason the editors of the Masoretic text decided to drop the 100's portion of the age.
If you follow the Greek Septuagint and the Samaritan Pentateuch with the six men listed above, then it puts the building of the Pyramids of Egypt after the deluge, not before. Also of note is the fact that the NT writers quoted the Greek Septuagint and not the Masoretic text.
Here's a link to the table if it's hard to read.
https://en.wikipedia.org/wiki/Genealogies_of_Genesis