One point often overlooked on the chinese issue... Quanity sold and the impact of that on American retailers, who employee Americans.
ie.. if 10 times as many chinese heads are sold as American, after the mark up, the chinese heads actually leave more $$ in the states employing retailers while allowing many new folks into a hobby they could not otherwise afford.
As to the potential of the Procomp castings, look at what Bryce has done with the Airwolf 220e heads. They are a great CNC SBC head using the procomp castings as a base to start from. I doubt Bryce would start with chunk or roll the dice with his name.
Look at Apple, if they made Ipads int he states, now one could afford them, they would sell very few and emplyee only a handfull of folks to assemble and sell them. However making them overseas, they are affordable for many and Apple employees over 60,000 folks stateside.
Sorry but it's just not a simple economics question or answer.