Kjones, that is not surprising if the head was replaced before 2009. The valve guide issue was not resolved until 2009 production so all the heads before that date were built with substandard valve guides. The only good news is that replacing the valve guides & doing a valve job will fix it. There are no new heads available except for the "reconditioned" heads GM sells for something over $1,000 which is 3 times the machine shop price of installing new valve guides and a valve job on your head. The real expensive is the high labor cost for removing and replacing the head. At a minimum you would also need a new head bolt set, timing set, gasket set, and of course the head work.
A compression test is the best way to determine the condition of the valves and the cylinder sealing.