The general industry consensus is that the Lycoming 320 and 360 series engines are among the most bullet proof engines ever made. My flying club has approval to fly them 3500 hrs between overhauls and they all make it, and that is 3500 hard hours being abused by students.
lack of use is a killer for any aviation piston engine. If you fly your lycoming at least every other week and change the oil regularly than there is no reason it will not go to and even well past TBO.