Originally I was only looking for 5-8lbs but Flyin Ryan has assured me the stock bottom end in the magnum can handle 8-11lbs with no issue. (he wants to be in the 15-18lbs range)
Which brings me back to why I was looking for a new crankshaft.
Normally I build BMW v8's and all the rotating mass is forged and pretty bullet proof, you have little to worry about while on boost even in the high teens. But being this my first American v8 on boost I want to tread lightly when it comes to either boost or damaged parts i.e. undersized cranks