I bought a high mileage 4.8is with 140K miles. I have documented history, but the dealership history in carfax is also very vague so I'm not really sure what items I should go about first.

On top of my list is replacing the valve cover gaskets and spark plugs. Anything else I should do while the mechanic is doing that based on the history below?

https://docs.google.com/spreadsheets...it?usp=sharing