wow. something i can actually give advice on. lol
I balance rotating asemblies at my work alot. mostly the rods.
2L8ULUZ2 is just about right. The pistons are already a matched set.
the rods on the other hand come from the factory balanced but they do a pretty half ass job doing it. ford rods are probably one of my favorites to do because theres not that much material need to be remove. the worst are the dodge.
to balance the rods, you have to weight the big end (where it surrounds the crank) and the small end (where the wrist pin go). if you add the big end to the small end it should be the total weight of the rod. to get the rods balanced you have to weight all the rods and find the lightest big end and lightest small end. then match all the lightest weighting big ends and small ends to all the others.
everything is weighted in the rotating assembly. Crank, rods, pistons, wrist pins, bearings, balancer, and flywheel/flexplate are needed to be balanced. its all entered in the computer and tells you how much its off.
hope that helps