First Mopar

Thanks to everyone for the welcome and compliments! Have a quick question, I have the 4brl, dual exhaust, I have great cruising power, just want a little more low end torque. My Dart takes a few to get to 20mph, but once she does, the needle will snap to 60 almost immediately and keep climbing, so I want to know, engine mod or or tranny and rear end rebuild or change to get just a little more low end. I don't want to launch, just a little more punch thats all.