All the better balancing shops in SO CA all claimed that they balanced all the rotating parts within + or- 1 gram shruggy
I ended up buying a Haus (SP?) brand triple beam gram scale and I mock up the rods to try and get them suspended half way up the lengths of the rods to check end weights, I've never had to send any parts back to a good balance shop due to weight differences in between the rods, pistons and so on shruggy All of them did say to not mixed the wrist pins though work
I have not bought any balanced engine assemblies from 440 Source, yet, so I can't comment on their balancing shruggy

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)