Your truck, standard, probably weighs in about 3600-3700 lbs. You're pulling off ~250lbs or more of weight. Engine, with tune/LT's is probably pushing 300+ hp at the crank. Through the slushbox, maybe 255-260 rwhp.
Your STOCK engine'd truck would do good to break 16's. I think you might be mid-to-deep 15's, maybe even high 14's with this setup and weight reduction. Stalls on the LS engines and a built trans work wonders. Mine in the TBSS broke off .6 - .8s from the 1320 times, depending on how I launched it.
Good luck and be safe!