This ain't the slight lope of the cam but is it a "pulsing" like a quick/brief miss with a split second or second of time between them? First I'd find out if a 950 idle is normal for that cam (I'm assuming no) & if Don curved the dist for you to be on manifold (vac adv activated at idle) vacuum & I imagine at 950 RPM the vac adv will be activated even if on ported which ma or may not be what he curved it for especially if it was expected to idle slower. timing may be excessive (when you retard it does the "pulsing" stop?), rotor phasing may be off. A valve may be hanging up or be burnt. I dont think the vac adv is the cause unless the timing is excessive & if so the timing needs to be adjusted elsewhere & keep the vac adv especially since Don set it up that way. Need more info/do some checking. IF you do lose the vac adv yes you can just unplug it & cap the hose then recheck/reset the reluctor gap/check rotor phasing as vac adv changes both of those & reset your timing