.023 is normal for a stock block. To get the proper quench (distance between the top of the piston and the surface of the head you want to use a head gasket that is no more than .022 inch thick and no less than .012. That will give you a quench of between .035-.045 which is ideal for controlling detonation. You can push it to .048 if you have to, but it would be better to stay with the .035-.045 parameter which is ideal. Quench is very important thing to consider when building a performance engine. I'm sure techinspector1 will confirm this.