NEED HELP! Backfiring!

Does this happen at all RPM's at WOT or just low or high RPM's or when exactly? Is this with the engine cold or hot or both?

Some thoughts: Backfiring in the carb can easily be ignition crossfiring or misfiring; the mixture tends to get harder to fire the more the mixture is compressed (more throttle make higher cylinder pressures), and that will make it more easily crossfire. How are your wires routed? Do they run closely parallel to each other? They need to be separated as much as you can and cross at sharp angles.

How close is the rotor pointing directly to the proper spark tower when it should be firing, or is it pointing somewhere in-between spark towers? (This would be a rotor phasing problem.) Is this the Mopar distributor?

Intake valves sealing can be another source of backfires. If this is at higher RPM's only, maybe the lifters are pumping up or something like that to hang the intakes open a bit. What is the cam and lifter type and setup?