A primary main jet change may help but be careful of creating a lean "hole" at part throttle before the PV opens. At cruise there is not that much fuel flowing thru the mains, but at part throttle there can be much more flow. A change which provides a small improvement at cruise may end up being too big of a change in the wrong direction under part throttle.
Another thought to consider is to try using your vacuum advance. This should provide for a smaller throttle opening at the same cruise RPM, and therefore move the slight rich dip up in the RPM band a little more. If the mechanical advance has been tweaked, the vacuum advance may also need to be limited.
I would not worry about the idle AFR that much; the engine is telling you what it wants. Optimal tunes are never "one size fits all". In addition to all of the variables in the engine (cam specs, exhaust sizing, intake manifold type, carb characteristics, etc), there is also the variable of how much load the converter is placing on the motor, and what sort of torque the motor makes at idle. In setup's like yours (and mine) a moderately rich idle is typical (IMHO).
