Whats better,grinding a crank or line boring?

Thanks guys.I do have a factory forged crank out of a 66 440.Was gonna have it offset ground with chevy journals to get a 3.92 stroke and yes,also have the counterweights turned down. Cranks ends up losing 5lb's? Could be that going this route gains me the lightest crank.Some of those aftermarket cranks weigh a ton.
My reason for asking is Im not sure the factory cranks can handle what the stage VI's will make.Im looking at at least 650 and more like 700,which I think may be just beyond it's limitations,even with rolled journals. Sure back in the day they used stock cranks all the time but power levels have kinda crept up since then.

Im sure the 440 source crank will be good enough for this power level. But what does it weight? Is it a big heavy pig Im going to have to lighten anyways?

I know that the mains/rod journals on these cranks usually have a radius fillet,and the procedure for fitting the bearings right is a pita.Either crank Id be doing that so it's a moot point I guess.