[Fixer]

I would relax and just go and use your good judgement.
Drive it, do a simple cylinder compression test and test the oil pressure which is very easy with a 911. This is very fast an easy and worth doing.
If the compression and oil pressure is good when at operating temp and it drove well thats a good sign. On to the body..
Look at the body or panel seams and that that they look correct or the same from side to side, look in the jambs for signs of a re paint. Look everywhere underneath for signs of an accident or paint overspray. Look for paint on the rubber glass seals etc..
Inside the trunk or boot removing the carpet and spare, look for signs of accident repair. You can examine the fender bolts to see if they have been removed and so on.
At those miles the driver seat should be in very good condition.
Good luck.