I found some important things that causes me to readjust my thoughts a little bit.

*[[2Sa 5:3]] KJV* So all the elders of Israel came to the king to Hebron; and king David made a league with them in Hebron before the LORD: and they anointed David king over Israel.

David did not become Israel's king until Saul died. I initially thought that his reign began when Samuel anointed him with oil. Saul served as sold monarch for 40 years.

*[[Act 13:21]] KJV* And afterward they desired a king: and God gave unto them Saul the son of Cis, a man of the tribe of Benjamin, by the space of forty years.

AND:

*[[2Sa 5:3]] KJV* So all the elders of Israel came to the king to Hebron; and king David made a league with them in Hebron before the LORD: and they anointed David king over Israel.
*[[2Sa 5:4]] KJV* David was thirty years old when he began to reign, and he reigned forty years.

SO, when Solomon said this:

*[[1Ki 6:1]] KJV* And it came to pass in the four hundred and eightieth year after the children of Israel were come out of the land of Egypt, in the fourth year of Solomon's reign over Israel, in the month Zif, which is the second month, that he began to build the house of the LORD.

That 80 of those years were by the sum of Saul and David's reigns as king.

What we find out is that God would not allow David to build the temple, and so, Solomon waited until David died. As i have already shown, the successor king is anointed and begins his reign, BEFORE the new kings father dies, for maintaining the family throne, THE THRONE OF DAVID. The fourth year of Solomon, is when David died. Meaning that when you add the twenty years work on the temple, to their 80 years, the temple complex was completed 100 years after the reign of Saul began. Adding 100 years to the 390 years [16 plus 374] equals 490 years of the kingdom. And this means that the 70 years captivity was for not keeping the Sabbath at any time during those 490 years. And it also means that children of Israel were ruled by the judges for 400 years to the year.

Blessings to all who keeps the saying and the prophecy of his book!
GB