Reduction in Hemi piston skirt length with the longer rod.......
The Hemi rod was less than a 1/10" of an longer the 440 rod. Doesn't make sense to use a longer rod, solely for the purpose of a 0.09" shorter piston that was already very heavy with it's domed top. Moving the pin up in the piston allows the piston to rock more & could lead to ring flutter or unseating the rings.
The fact is that Chrys already had a very beefy rod in the six pack rod....but chose to go to a new forging of a longer rod.