[Joe Bob]

Any tapping of the head with the possibility of getting shavings inside gives me the willies....I would check compression, and leakdown. If the numbers are low, pull the head(s) do a valve job and plug the smog injectors with the heads off the engine....
Mom always said....there is never time to do a job right, but always time to have to do it over after you screw it up the first time...