$30K is a killer deal for that engine. One of the race teams that I work with has spent way more than that on engines that make less power. Some guys just like to roll their own stuff but production line stuff is better and cheaper as long as the production line is properly managed.
There are yes's and no's to what you said about production line stuff, but, if gauges are implemented correctly, it will be good when it gets to your door. My guess is this is a small shop GM outsourced to assemble these...And not a full on regular production line like the old Marine engines.
