Procedure to restore Production from Sandbox (Dev)

After upgrading to Ver 9, we have been unable to upgrade Project Automation 2.4.4.30.  Had a ticket open with support since April 2018 and was informed today that they could find no solution to the problem, so they closed the ticket. 

I had no problem upgrading Project Automation in the Sandbox, which is our Development (Dev) environment.  So I am seeking a procedure to delete the Production (Prod) environment and recreate it.  This is what I am proposing - Plan B.  Will it work?

• Take a backup of the Prod data and also copy each of the tables to excel files ( for plan C)
• Delete Prod
• Minimal copy Dev to new Prod (sandbox) - Dev structure is the same as Prod.
• Upgrade Prod to a production environment
• restore backup to the new Prod

What are the constraints or anticipated problems?