Steve hit most the high points on the head.
I respectfully disagree with Bob's point on the valve guides. I don't think it is a foregone conclusion that
all these cars will need their guides replaced. Just like the various 964 problems don't affect all cars. That being said, some of the recent posts indicate they seem to reach critical wear very suddenly. Since I have an 87 with 68K, I have to be optimistic about this one
At 88K miles, it should have a new clutch. Which means you'd like to see the receipt that shows the update kit installed. The O2 Sensor is near end of life. Would be good if the Cylinder Head Temp sensor was replaced with the updated 2 wire sensor. As with any used car, it's all about records and condition - how was the car treated?
Good Luck!