Does anyone have a Test Plan for upgrading P5 to P6v7? Or anything close?

We are upgrading from P5 to P6v7 and, as is our custom, we need to fully test the capabilities of a product prior to putting it into production.  Our production environment is substantial and the infrastructure complex, so we can ill afford to wait until completing installation to discover that a printer driver in Oakland is preventing an activity modification in Cleveland and crashing a desktop in Tampa.  Hey, it could happen!

So, my task is to create a "test plan" that I can foist off give to a group of conscripted volunteer planners and project managers to explore every aspect of P6v7 to assure ourselves that it works as designed on our hardware and infrastructure.  With me so far?  Good...