Jeff,
I know a little about the big-blocks.
I had an original 1969 M-Code 440 Cuda w/3.55 gears.
You had to walk-it-out off the line, until I changed the rear..
Drum brakes, manual steering, drove like a truck.
Winding roads was not its specialty, but in a straight-line
.
Thought maybe the E-Body would hook up better, with a little more mass-weight. Never had an E-Body Mopar, only A-Body cars.
From what I hear, the engine compartments are a little bigger
Sounds like you knew had to tweek the ignition.
Paul