Design Document - 12c to 19c on ODA

We are in process of upgrading our 12c DB(SE)to 19c(SE). The old hardware (ODA X6 Model) will be decommsioned and 19c will be running on a new hardware (ODA X8 Model).

To prepare for the upgrade, we would like to start with the design document.

The design document will have following information at minimum:

 - Information about Current Hardware (CPU, memory, OS etc.)

 - Information about 12C DB

 - Any concerns

Based upon the current information, the 19C DB will be designed (tuned) for better performance.

Appreciate if someone can guide me to any useful link that will help me to prepare the document.