Guys
cast cranks are stiffer, the do not flex
if they flex they break cast cranks like detonation less than forged cranks
forged cranks are a lot more giving which is why you run more clearance with a forged crank
We ran the 199 AMC 6 cast crank (3" stroke) with 60 POUNDS of boost making 1200 hp short burst and 1000 for hours
(Champion Spark Plug dyno with Dick Jones at the controls)
no engine problems at Indy
we had both cast nodular iron and "ARMASTEEL" both worked
nothing special on the bearing clearance but oil flow opened up to the max to cool the bearings (but do not know if it was really needed)