crankshaft help

Funny you should mention 273, i asked a couple of my mopar friends about that, and they say that even though the 273 had a steel crank (in most cases) the throws on the cranks cant take the harmonics and blow apart after piling on the hp, and my machinst said damn near the same thing... now im not saying this stuff, its the people i talk to.......thats why i getting advice from everybody!