Under $4k budget build LA360 build

Captainkirk said

Shot peening compresses the grain structure of the metal, "pre-stresses" it and makes it more resistant to cracking.
A shot-peened crank will have tiny pock marks (as Rusty mentioned above) on the non-machined (counterweight) areas, just as if someone had pummeled it with thousands of tiny lead shot pellets...which is exactly what they did.
It appears the weakest crank of the 3 types (forged, cast and cast/shot peened) is the cast-only crank which apparently only left the factory in the '72 340 (now you know why I changed mine to forged). My sources list ALL 360 cranks from '71-'86 as cast/shot peened. Hope this answers your questions!

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Well now, that's debatable. Remember, there's a difference in "just cast iron". There's "just" cast iron and then "nodular" cast iron which is much stronger than plain cast iron. That's what made the 351 Cleveland cranks famous. They routinely spun to 9500 plus RPM on NASCAR tracks. Yes, of course they were professionally prepared, but nonetheless, they were indeed nodular cast iron. Very strong. If I am not mistaken, all the Chrysler cast cranks are also nodular iron. That's why, although it does happen, you seldom see broken factory Chrysler cast cranks. They really are that strong. That's exactly why I always give the advice to use what you have if you have a cast crank. The will last plenty long.