Please don't attack me for asking another question about engine building. This is my first time doing this, and I need a bit of clarification.

I'm building a 2056 with KB flat-top pistons, stock cam and D-Jet. I just got my heads back from the shop, and they said they had to fly cut the heads .015". Does that mean I need a shim of .015"? I don't mind increasing my CR, as long as I can retain pump gas. I'm not trying to build a high HP engine. I just want to make sure I'm not going to smash my valves into the pistons.

You MUST measure the deck height and it would be good to measure the Comb chamber volume (but not absolutely required).
With the .015 change and stock cam you would have nothing to worry about regarding valves hitting the pistons.

You want to target a stock CR (or slightly higher) but you need the two bits of info above to do that right.

Install the barrels and pistons, you need to measure the deck height, depending on your desired compression ratio.
Deck height should be 1 to 1.5 mm, lower number means more compression, adding shims to the bottom of the barrels increases deck height.
Flat top pistons increase cr.