Troubleshooting Head Components

Head diagnostics would vary by member wouldn't it? (The /6 would have nothing to do with it)

Besides that I'd pull the valves and look at the overall condition of them, you can't see the sealing face or much of the stems while still in the head. And then maybe not til you start trying to machine them on a valve grinder (though more experienced machinists can tell more by just looking at them as to whether they're reusable.)
For the experience I'd pull them, and either bead blast them or run them on a wire wheel for starters and then go from there