I personally wouldnt worry about a cast crank, a friend of mine ran a Vega small block drag car for 12 years with a cast crank...never a problem at all. Is this a drag car only, or street car? 500 HP small block is pretty extreme, that's why Im asking. There is some concern about harmonics with forged cranks too, you might want to do some reading up on that topic. I just built a 505 big block chevy, and used a cast crank. Im not worried about it at all. You posted this in big block section, you might want to move it to small block and see if you get more responses.