[blykins]

Aftermarket cranks are not cast iron. They're steel....cast, forged, or billet. Take your pick.

The engines that you're looking at for $15-20k are not cast iron cranks. At the very least, they're Scat cranks....cast steel.

There are some manufacturers making forged FE cranks now. Plus Scat will make you a billet one for $2-3k.