In my experience, 3.8's hold up for around 200k miles, but that's the N/A ones. I don't know about the supercharged models...but being that the 3.8 is dang near bulletproof, it's a safe bet you'll get a lot more miles out of it.
The trannies are also excellent units. I wouldn't expect problems here either.
Other than that, just check for basic things. Is the interior in good shape? Does the car track well? Does it run smoothly? Burn oil? Use common sense and it should be fine. Don't get your heart set on the car, you have to be prepared to walk away if it's not what you really want.
An it harm none, do as ye will
Approximately 79% of statistics are made up.