Piston Weight And Balancing

In preparation for building the Mk3 bottom-end, I weighed the rods and pistons.  The rods are virtually identical with only a 0.28g delta.

The original STD AE pistons, rings and pins have a 1.85g delta and the new individually boxed, Norton Villiers AE pistons, also STD, have a closer 0.8g delta, which is good.  However, the delta between the original and new pitons is 4.13g, with the news ones being the heavier.

As the factory to my knowledge only carried out a static balance (correct?) and I assume had nimindl mass counterweights, the variability in piston weights other than left to tight, if that was actually checked, would not have been accounted for?

Several years ago, after I had the Atlas crank balanced (to 70%) by Bassett Down, I found preferable new original dished pistons and these were 5g lighter than the dished, slotted (hence the change) pistons that the balance factor had been set up with.  Bassett Down said slightly less piston mass was not a concern, as it would merely result in a slight increase in the balance factor, which was in the right direction for faster road riding.  

I had not planned to get the Mk3 crank dynamically balanced, as it is not as important as for an Atlas and perhaps 4g was within an expected piston weight tolerance for static balancing?

Any thoughts?

Andy