correct way to store cranks and heads

When you buy a crank kit from an auto parts store, they are not stacked on end in boxes. They are stored on shelves, laying flat on their side. Same as new cranks from any dealership, vendor like Summit, Jegs and everybody else.

If it was true that it warped them, you'd have a slew of people with bent cranks and warped heads. That ain't the case, so it's an old wive's tale if ever there was.