Thanks all, great advice here! Given the time of year, I agree with @oldjeep and @Gloersen and plan to put on the new heads and hope for the best. These are GT40 heads and the Machine Shop is telling me that these heads have a crazy amount of clearance. If it was December I would most likely pull the engine and do a total refresh. As @oldjeep said, once I pull the pan I would pretty much have to do a total refresh....maybe next winter. @Mark_Matis, I believe you hit the nail on the head as there was significant blockage in the cooling passages which I'm sure contributed to the cracked head and is probably related to low water levels this spring.