using a oilite bushing can gives some wearing on the inputshaft .
when a oilite bushing is wearing out it can gives problems because the clutch dont came ,,free" because the inputshaft is out of aligment.
a pilot bearing can destroy your inputshaft when this failed, or damaged by aligment the inputshaft by mounting the ZF.
My favoriete is the oilite bushing.
Simon