Pretty much any combo I have raced( assuming the convertor is right), leaving at just off idle, at 2000 rpm, or off a trans rake at varying rpm's the cars have always 60 footed within at most a hundredth or two no matter the launch rpm or type.
If your convertor is good, I would bet not re-inventing the wheel and leaving at 1800-2000 rpm off the Foot with the chassis not " tensed up" will or should result in as good and repeatable 60 foot as you are likely going to get.
At your ET, the 60 should be 1.50 ish or so. The fact you are so far from that and it's hooking makes me think launch rpm/ style isn't a place to be looking.