Dear Drew;
The block needs to be 'square' to have even compression. Not so much for stock, but 'high performance'.
In the 1950s & 60s QC on these 100 horsepower engines wasn't that great. Today; On a 'Hot Rod' one It's necessary to have all equal.
Imagine if the crank isn't straight, say closer on #1. Then each cyl. going back will have less compression that the one before.
Like a house with the foundation on a slope.
And yes, all cranks should be ballanced & magna-fluxed.
