[Rev]

With a 408 and a moderate roller cam you will probably have a torque monster anyway. The problem with too high stall is that in normal usage, the convertor never "couples" and so is always slipping and generating a lot of heat, Heat kills trannies. I think for a street driven car, 2500-2800 is probably all the stall you really need. High torque raises the stall rpm anyway.

Rev