The only thing trans related that would cause it is the converter. If it worked before, it should work now, unless something happened to it. Dropped or something worked its way inside. Can you feather the throttle when easing it into gear and see if it stays running? Btw, where is it idling now with the new carb?can you get the idle down to 800 range, give or take say 50?
At this point, you may need to either find someone in the area to take the car to, or someone in the mopar community in your area to come over and check it out. Trying to diagnose things like this over the internet, or over the phone or whatever can be impossible. Some problems can be so common that the answers are simple, like a bad ballast resistor, but other times not so much. If i were closer i would jump at the chance to help. For my own benefit and experience as well as yours.