Small Leak In Cylinder Head

I have a pair of Edlebrock Performer cylinder heads and one combustion chamber has a small leak. I poured water in the combustion chamber and all but one holds water. The one that does not hold water is not a big leak, it slightly seeps out from the valve guide. How much attention does this one cylinder head need? Just a new valve guide and lap both valves? The arrow shows where the water is seeping out the guide.

I lapped the valves and it does not leak anymore. I have a lot of dirt and particles on the head, and inside the chambers. Can I use car wash soap and a garden hose to clean the head?