In your teaching on Hebrews 7A you mention that according to 2 Peter 2:5, Noah is the 8th preacher of righteousness. It seems he would be the 10th. Why do you skip Enoch and Lamech?
The Order of Melchizedek is a priestly order that an individual holds for life before it is passed on to the oldest son at death. In the case of Enoch and Lamech, their fathers outlived them, so they never held the position. Therefore, there were only eight men who held the position from Adam to Noah.
For more information, please read What is the Order of Melchizedek?