It's sounding more and more like an 11" converter isn't the way to go here, IMO. Perhaps a "tight" 10" that can provide reasonable stall w/o being too slushy? Wonder what Paul at Turbo Action would recommend...

Two 9.5" experiences: In my car, Dynamic (Lupo) nailed it IMO. In Mike Hynes' car (heaver, torque curve much lower, less gear, etc.) his custom-built Dynamic was a big miss. His car felt much better when he went to a bigger converter to tighten things up, and it picked up MPH on the track, too.