i have built engine big blocks that made big hp on cast cranks they work fine to 600 hp . hears some things to think about cast cranks when hit with a hammer they don t ring like steel crank that is harmonics cast do not ring as much so they do not trans harmonic like steel.this runs thru the engine not good. but cast cranks do not like to much twisting.a cam with 4 7 swap can help this .if you think you need a steel crank think a bout this .oil running clearance on rods@mains and bearing type