If cracks make you loose sleep and you are gonna pull the heads have the EQs ready, your heads are cracked. If you have seen thousands of these heads running just fine with cracks in them like I have don't worry about it.

Also I have built tons of these engines with bigger cams than that that see daily use under severe conditions and never seen a stock valve fail except the ocasional burnt valve when nearing 300,000 miles. I am currently running .575 lift and 222@.050 duration 12 to 1 compression in my truck with the stock valves plenty of 6500 RPM blasts and no issues.