I had cam bearing troubles with the 392 in my 73 1210 at about 180,000 mi. I knew it was having trouble as the oil pressure was getting lower all the time, it finally took a tooth off the cam gear. All the cam bearings were shot, and the front one was the same as gone. We pulled it down, put in a cam, lifters, cam bearings, rod and mains. It now has 330,000 mi. On it and has never had the heads off. I don't think the sv engines are hard on the cam bearings, I just think the technology of the cam bearings doesn't match the rest of the engine. It still runs just fine and will use a quart in around 1000 mi., still a lot of life in the engine.