how is the block made? crankshaft placement goes where
Side angle side where side is crank center to deck distance and equal on both sides and angle is V angle, 60 or 120 degs for firing order purposes. The point where the two intersect is thus fixed and that is what will be measured and set up by heavy duty precision machinery during a line bore operation.
Block will be decked and cylinders will also be bored to be true to the crank center as well regardless how close it might be or how perfect the cylinders and crank case ended up being.
Its all final machine work, that stuff is impossible to do individually with hand tools.
In other words he welded in solid rectangular slabs and caps and had the whole thing bored as one. You just have to be crude ballpark on the rough block, the final machining takes care of the rest and ensures everything is perfect.
You can start with a giant lump of rock if you want. As long as you line bore, deck, and torque plate cylinder bore, you can have a working engine block. Those are the three most important relationships. Even cylinder bore centerline to rod journal can be slightly offset within reason , that's why all engines have loose crank endplay and rely on crank thrust bearings to allow for that tolerance and to precisely locate the crank during final assembly.
Any errors resulting from making a custom block by hand will be ironed out at the machine shop same as it is with every imperfect sand casted factory block.