Installed new engines in January and ran for about 2 hours and had no issues. One engine then developed a slight leak after an additional 1.8 hours of moderate running at cruise speed, milkshaked with only about 1/2 quart of water.
Becasue it was not climbing the stick and pushing out the top we knew it was only a very small leak.
We changed oil and filters and again picked up about a quart of water in 120 miles of straight running. (we did stop a couple times and check for significant volume increases)
We pressureized the block and found a very, very slight leak in the head gasket. The water was dripping into the valley. The only way we could tell was to remove the intake and just watch and watch and watch.
We removed the one head replaced the gasket with some additonal sealer, wiped everything down in the valley and under the valve covers as much as possible and we were off!
3 very knowledgable people looked at it with their various opinions. If we would have listened to the first two we would have purchased new headers and still had the leak. A little more due diligence paid off.