A lot depends on the mahining on your block. I typical block, decked with an older miller will typically be out of flat and parallel by up to .003", the bad ones as much as .020" off over the length of the deck. So when you say you're building with quench you have to take into account the accuracy of the parts and machining. Minimum safe distance for a forged piston/steel rod engine can vary from .015-.030" depending on the compression height, the bore size, and the rpm of peak power. Normal "safe" is no closer than .030. I target .035. To get that accurracy I have to index and correct the cranks' stroke in some cases, match and set rod lengths, align hone the mains, and have the block square decked. Only then do you have the package that is accurate to run tight. Tighter is better right up until they hit. Anything farther than .050 IMO is not worth aiming for as the cost of machining will be great for little or no benefit.

Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.