It may just be a simple working relationship, but it doesn't have to be that way. This industry isn't a drive-thru window at your local burger joint down the street. On the surface, it may look like a basic goods/service scenario. However, building a relationship with your engine builder is very important. If you really think about it, the guys that will be machining and servicing your engine will be in contact with you for weeks to come. It's important to establish an environment of trust and it must be built between the two parties in order to maintain good working order. The customer must feel comfortable asking questions about their engine/parts and the same goes for the shop when attempting to answer them. Don't worry, they won't bite your head off for asking a question. Besides, it may prevent a problem during the build later.
Knowing first-hand, there is nothing more distracting than a pesky and irritating customer who preaches that they aren't in a rush, only to find out days later they were expecting the engine yesterday. Word of mouth spreads quickly, and with the abundance of blogs and local automotive forums these days its practically instantaneous. There isn't any reason a race shop should get a bad wrap if it's not justified. My advice? Choose and engine builder you trust with your own kids. Afterall, wouldn't you most closely associate your engine as your very own child? I would. So, take your time and do your research. Happy motoring.