I put the Speed Demon 750 on our 1967 400, not sure I got the Idle mixture just right but I will tell you that was the single best improvement that car has seen yet. It is extremely responsive. If it's anything like the speed demon carbs, you will be happy with the carb once it's adjusted. The one I bought was flow tested by the factory but was still running rich at idle. It's much better now!!!
Brent