I had a custom built 10 inch converter built off of my dyno sheets (612 HP at 5500 RPM and 644 Ft. Lbs. at 4500 RPM) for my old street and strip Duster, it would foot stall to 2300 RPM before sliding the front tires through the staging beams at the races, it would flash stall in first gear around 4200 RPM. I was happy with it until I broke it and swap in a Turbo Action 8 inch SS/AH converter I had taken in trade and never used, that converter would foot stall over 3300 RPM and flash stall to 5200 RPM, it was way easier to drive on the street and at the track
It pick my car up .2+ ET and 2.+ MPH in the eight mile, which really surprised me
My message is buy the best one you can get, call around to the better converter companies and see what they suggest, I've used several 8 inch converters on the street and for racing also