Just to make sure cam "end-play" is not the same as "backlash" to me. Cam end-play in my 1992 HD Dyna S.M. say's .010"-.015", your .008" should not make a great difference. Gear pitch as Frenchie described above is what I sometimes refer to as backlash. I'm only bringing this up so we all know exactly what we are describing to each other to help solve your ??. My S.M. says incompatable gear pitch can result in a "whine", then goes on to state "proper gear clearance will give a very slight whine when engine is hot". You may be noticing more of a whining sound than I would?? As for being down on power, all I can guess right off is the breather gear may be mistimed and not venting precisely.