Hemi's are hard on guides...on the intake side. The short sweep/radius of the intake rocker arms side load the guide quite a bit. The exhaust not so much as they are quite long (flatter arc) The biggest issue with stock rockers is they all need to be ground to correct true up the ratio. In blown application you used to see Roller rockers on the intake side and non rollers (Kluff rockers) on the exhaust. Also time spent on centering the contact patch of the rocker to valve stem will greatly reduce guide wear. I have gone as far as re-positioning rocker stands to correct this.