Standard bore size means you need standard bore pistons. The pistons fit the hole with very tiny clearances, so they have sized properly. If you want .030-over pistons, you need to bore the block .030" oversize.
Its specific enough that many machine shops won't bore and hone the block until they have the pistons in-hand to measure them. The final .001" of honing depends on the actual measurement of the piston since slight variations mean that all 30-over pistons are not equal.
About the only way you'll find standard bore blocks is if you buy a new one. Unless an engine has VERY few miles on it, its not a wise idea to rebuild it without machining the bores. Bores wear in funny patterns. They tend to become egg-shaped because of the side loads on the piston from the rods. They also tend to wear more in the upper part of the cylinder since that is where most of the action happens. Putting new pistons and rings in a used cylinder is like putting new linoleum on a buckled floor. The Linoleum is perfect, but the floor under it is lumpy. Its best to machine the bores. Depending on the amount of wear, it might only take .010" to clean it up, but pistons are hard to come by. Going .030" over is not a bad thing at all. More cubes, more torque, and freshly-honed bores that are as good as new (if not better)
Last edited by curtis73; 05-13-2009 at 10:13 PM.