Steaming Hot Telltale - 1989 45 hp Mercury - Part 4

I’m at my wits end about this over heating condition. I really thought I had this problem solved. I’ve done everything except pulled the power head to fix this issue.
Could it be it just needs a complete new water pump kit? That’s going to be next before I decide to pull off the power head.
If anyone has any suggestions that might help I would really appreciate it.
Part 1 - No Spark - Switch Box, Stator or Trigger
• “No Spark” Is it a Bad...
Part 2 - Over heating even after installing a new impeller
• New Switchbox Regained...
Part 3 - Carb Clean & Install
• 1989 45 hp Mercury - C...
Part 5 - overheating - Try This
• 1989 45 hp Mercury - O...
Part 6 - Overheating - Problem Found & Resulting Carnage
• 1989 45 hp Mercury - O...