Get the pre-purchase inspection done.
You can visually tell if those parts have been replaced. Some of those bolts are painted blue. Replacement bolts aren't painted. Does he have receipts for any of those parts? Does he have maintenance record/history. If you get the PPI done at BMW dealer, they can look up and tell you about the history of the car and tell you if there are any open recalls/TSBs pending on that car.