Quite honestly Richard, all this discussion is irrelevant for our engines, they are not highly tuned, tightly clearance controlled machines that require such heavy investment in sophisticated balancing. I would suggest that the "matching" you have achieved to date is good and the polishing equally great, it maybe the the polishing that creates a smoother engine too as it whirls through the air/oil vapour, but either way, unless you invest in some sophisticated process you have what you have, so to speak - maybe worth assembling the pistons now and then doing a recheck on the comparative difference end to end, but I'm sure you could keep going with this forever to try and achieve perfection, but for what purpose?
I note that Muskrat hasn't commented here nor RR and maybe they are perhaps the most experienced with tuning and racing these engines, to comment on the effects of balancing and smoothing all the parts.....