How much decking is to much?

What's the machine shop(s) have to do with the block not being square from the factory? I am talking about two 340 blocks that were decked at two different machine shops (about 1,500 miles apart from one another) where they both found the same discrepancy, namely they found the passenger side deck was higher than the driver's side deck (and neither would clean up after the first cut). We measured the piston deck height's before hand and knew the problems going in.

I went back and re-read what you wrote and I stand by what I said. You clearly state the shop gave you back a block that was still uneven side to side. They need to find a new profession cause the one they chose don't suit um too well. They told you to rely on different head gaskets. What a effin joke.