A few things have gone through my mind. The weight of the rotating assembly and the length of the stroke. I've had 383s that had better throttle response and low speed performance. I've thought about advancing the cam. I've had good results with that in the past. It's a heavy car and I'd like to keep the 3.54 gear in it. That in itself presents a bit of a challenge. In this situation it seems like the automatic is more forgiving. Anxious to try some different things and hoping to get the chance soon.