I was refrencing the actual exterior mounting surface on the head, the internal chamber is angled. I have found no abnormalities on any of the engines I have gotten in stock from a basic visual inspection.
www.dawghouserc.com is up now and I hope to get some more of these engines in the field shortly. I also have a couple going out for extensive testing in multiple prop/exhaust configurations. I hope to get some good feed back on this to get out to the consumer...