If this is a street strip car, then the converter will need to be somewhat tighter than a race unit. For race only, I would be looking at something that will stall about 5600 to 5800, with shift points likely to be 6800 to 7,000 max. Street, that is a matter of how much slip you are willing to tolerate. With 276 @ .050 duration, I would guess you can run something as tight as 4,000 stall and still ET pretty well.