I recently replaced the left engine with a RAM engine and RAM modified the 350hr right  existing engine.  Serviced the props and Gov on both engine.  The right engine has a vibration at cruise.  Balanced the props, replaced the mags,mag harness,spark plugs and shimmed the motor.  Climb out fine, level cruise vibration continues.We have looked at any moving part that is hitting cowling and adjusted same. Motor runs great, turns up, fuel flow and bo signs of engine issue. I am looking for solution? Your experience would be appriciated!