Gifted a 911 Turbo 30 years later
 

I have been a Porsche "student/admirer" since age 20, now in my 50's a dear friend is giving me something I couldn't afford at this time., a 1990 911 twin-turbo 3.6 bored producing 570hp, 60,000 miles! I am silly with anticipation, the day is tomorrow.
My first Porsche was a 77 911S (new). What am I in for? Good or bad?
I am concerned with anyone changing/building onto Porsche's original design in terms of durability, reliability, and engineering. Anybody have experience with the 3.6?