I did some pretty serious research before i purchased, secured info from Guy and several others in the "know from experience".
A billet rod is plenty good for us normal guys and fine with decent tuning to 800+ as reflected in Caspers longevity. Nasty Girl had billet rods as well IIRC, didn't she? A short lived motor, but never heard she squashed the rods.
Long story short... If you plan on seeing the other side of 800 ++ HP.... pay the extra for forged, IIRC they may be a little lighter depending on the maker.
At this point they are all overpriced.
If i was to buy again i would look for a stroker Chrysler rod and see if i could adapt it.... Didn't they make a HEMI stroker rod close to 6.4 center?