Correct Torque Converter?

if you look close at my avatar you will see a 70 Charger SE behind the 68 Barracuda...( it was my first car) a 383 Magnum car originally I ran a 440-6 and a solid 550ish roller at the time of that pic..(still had the 383)... I switched back and forth between the stock Magnum TC and a J-converter.
the J was about 3/10s quicker at the track. both ran great on street.