Search BMW R1200RT and need a purchase consultant

Hello, I’m looking for a BMW R1200RT and don’t know exactly if a mileage of over 120,000km is too much. Has always been maintained at BMW and clutches and valves were made last year. How long will an engine last with annual maintenance and human driving style and what do I have to pay attention to with a Rt besides the brake power amplifier? Maybe one can help me, I am unfortunately a student and therefore I can’t afford a total failure.