It seems that since you had the slow reaction with both the small block and the big block that it could be in the transmission. Your car weighs 2160 and runs 8.64 and your 60ft was a 1.25. My car weighs 2650 and has only run a best of 8.90 and the 60ft was a 1.23, which I have been told is slow for my ET, but I leave at 4400 and only bracket race. I have a delay of 1.055 in my box and the transbrake is a full-tree brake not a pro-tree. It seems that reverse in your transmission is not releasing quickly enough and dragging, which would cause it to not 60ft and react like you want it to. I would think at your weight that it should have a 60ft of at least 1.19, and that would get you red.
Bill Mitchell