Torque converter

Ok guys and gals. I no everyone has an opinion so let's hear them. My lil Dart is running ok, but I seem to be leaving some on the table in 60'. Car has run the best of an 11.92 @ 112mph but with at 1.68 60'. I feel the car should 60' around a 1.58. Car weight is ball park 3200, 390hp at the crank, 406 torque. 28" tire, 430 gear with a 727. Have thought of the 904 but I still feel the converter is the issue. I bought from a friend that runs SS hemis so it is probably too much. I think it is a 8". Engine is a stock bottom end magnum, shifting at 6000. I also have been leaving at 2200 to 2500 rpm. I would like to know what similar combos are running for converters and what your 60' is.