CNC Motorsports is based out of Brookings South Dakota and have a large industrial based shop where they build engines and offer deep discounts on mail order performance parts and build kits. They have a large machine shop with a half dozen assembly staff and run a really good business with some great feedback. I have dealt with Jason there in the past and he's a good guy to know and work with. They have a great website and tons of positive feedback as a reputable builder at an aggressive price.
I priced my most recent engine build with
Doug Herbert at Herbert Performance as well as Jason at CNC Motorsports. Both had an aggressive price that killed most other competition in the market, and I ended up building a high end 565 through Herbert in NC. Shipping was free in the continental US and it was built and shipped in a couple weeks from the time of order, all with choice components I might add.
Can't go wrong with any of the above builders in my mind.