Bora Questions: AJM Engine, 85kW Performance

Hello everyone,
I had already asked about this here, but to improve clarity and avoid going off-topic, I'm creating a new thread.

I am planning to buy a Bora Variant TDI with the 85 kW PD AJM engine. The car was manufactured in March 2000 and has 80,000 kilometers on the odometer.
Having read about the AJM engine here and elsewhere, I'm starting to have doubts about whether I can drive this car worry-free for the next ~120,000 km. It seems that problems with the cylinder head gaskets, common rail injectors, and timing belt (+ related components) frequently occur after around 100,000 km. I am familiar with the maintenance intervals, as well as the (horrendous) costs associated with repairs.
My question now is: are these isolated incidents or a widespread phenomenon? Are the defects that occur more dependent on driving style, or are they defects that are to be expected in any case?
The 115 hp PD engine is sometimes referred to as the 'experimental PD' by VW. Is there a specific date from which the AJM engine received fundamental improvements? Is this engine even worth recommending, or should I reject this otherwise very good offer?
The car in question comes from a trusted source and therefore has a documented and verifiable history. The seller is reliable, so we can rule out common issues like lack of proper warm-up or neglected maintenance.

Many questions for a newcomer here, but I still hope to receive many experiences and insights from you all , the more one reads, the more questions arise...

Best regards,
Gerd.