Engine builders, piston Fitment

The instructions are available on the KB site. Clearance depends on bore size, the piston material, and the use, and it's set by the final bore size.
Usually KB hypers are .0015-.002 for light use. .0025 for higher performance. You can run more if you have to but they might get noisey.
Forged usually want more but again, it depends on the material. anywhere from .0025-.004+.
Cast factory are a little tighter than forged, not as tight as hypers.