Funny you say that, there is actually a channel from over there somewhere and the do stuff like that, those guys are pretty creative....but they actually get stuff repaired, its quite interesting. "Pakistani truck" I think its called
Honestly a cast iron head , for years I'd "cookie wheel them" and bolt them up, never an issue.. cast iron is very forgiving. Now if you go aluminum head on cast block you have to pay attention to the machined / sealing surfaces. That board and battery method would work( as in the engine would seal) to clean the head, I don't know about truing it if it is warped but that is the illusion, how many here have actually seen warped cast iron heads?
Another thing that board method might do is identify low spots like guide coating body work, but a straight edge and feeler gauge would do the same...