I would go for the S&S kit as it has a better inner cam bearing Thorrington i think which has more needles in the bearing making for better weight spread,
the harley fits have less needles in the bearing.
The aftermarket kit use torrington and the SE (stock) use a INA style, I will have to say that I have not seen a inner fail in a T/C though, evo yes. Ihave seen outer bearings that are blown apart the inner cam surface badly damaged and the bearing when removed looked good rolled smoothly and had no damage to be found. I do replace them but then seem to hold up well in the t/c