I'd worry about oil in the vacuum system. If the vacuum pump gives up, you will lose brake assist dramatically increasing braking distance, and it could send shrapnel into the timing chain.

The tech who checked your car was probably in diapers when your car was first sold. He heard the loose belt tensioner and assumed rod knock.

In the future, get the inspection done before you buy the car

Sixto
95 S420
87 300SDL