Just how low can you go with the deck clearance? Now you always see the .040-.045", sometimes I've seen .035", but it depends on many factors.
Such as:
Max RPM, Piston to Cylinder Wall Clearance, Rod Bear Cl, Main Bearing Cl, Piston Pin Cl, Materials (Cast or Forged) and how you measure the deck clearance. If you were to split hairs, I suppose you would have to include oil film thickness.
Most people rotate the crank until the piston is at it highest point in the cylinder. But when the engine is running on the exhaust stroke, all the clearance shift to let the piston travel a few thousands higher in the cylinder. So when someone says they have .040", they really only have maybe .038-.037" when the engine is just idling.
So what's the lowest deck clearance you have successfully run and what parameter did you use, to best of your memory or notes ???