I have 64,000 miles on my 2000 996 and it runs absolutely perfectly - which includes about 800+ track miles. I'm guessing my engine has a lot more life left in it.
Personally, I'd call Laura Hergesheimer at Hergesheimer Motorsports down here in SoCal. Mark and Laura own the place and have been in the business for 30+ years. Laura's very nice and friendly and knows more about these cars than just about anyone. She'll give you a straight answer. She's a fellow Pelican, btw, but doesn't post much these days.
http://www.hergesheimer.com/