340 Piston Selection

How do you set the deck height without the Pistons? Are you going to cut the decks until they are square? Or cut them to a random number? You have to take into account variations in rod length, stroke length and even the compression height of the Pistons.

You cut the deck to get what you want. Not to a number. Way too many variables to cut the deck to say 9.560 or any other arbitrary number.
I usually just have the deck cut untill it's square, measure and go from there. I like to remove as little as possible from the deck surface.