i had a steel 440 crank and '73 cast 440 crank.. put them both on the bathroom scales and they weighed the same. i know it's not precise weighing but it was what it was .i wouldn't be afraid of a cast crank at a reasonable power level. reasonable is maybe 500hp to me.
I've weighed both as well. 73 lbs. as I recall regardless of whether they are cast or forged.
'63 Dodge 330 11.19 @ 121 mph Pump gas, n/a, through the mufflers on street tires with 3.54's. 3,600 lbs. 10.01 @ 133mph with a 250 shot of nitrous an a splash of race gas. 1.36 60 ft. 3,700 lbs.
.i wouldn't be afraid of a cast crank at a reasonable power level. reasonable is maybe 500hp to me. 
