Complex sentence: He took the post of Permanent Guest Conductor of Amsterdam's Concertgebouw Orchestra in 1978 and remained in that position until his death from a heart attack on the sixth of March 1981, the day after he conducted the Norddeutscher Rundfunk.
Split into simpler sentences: He took the post of Permanent Guest Conductor of Amsterdam's Concertgebouw Orchestra in 1978 and remained in that position until his death. He died in Amsterdam from a heart attack on the day after he conducted the Norddeutscher Rundfunk.