Dave, have you considered using coil springs in the rear instead of stock type leaf springs? Coils are infinitely more tuneable than leaves. There are dozens of different spring rates available and, by using stock-car style weight jackers, you can infinitely adjust the pre-load on them. I have coils with weight jackers in the back of my coupe and it is NOT a posi rear end. By giving my right rear spring a couple of turns of pre-load on the jacker, the car launches with almost no wheel spin and it's equal on both sides.

Ooooh! Throttle stops, delay boxes, stutter boxes, and even tranny brakes; DIRTY WORDS!! I hate them all. All that crap should be outlawed; use an old-fashioned line-lock and make the drivers DRIVE. I rarely go to the drags any more because it's a bunch of slot cars where everything is computer controlled except the steering wheel. If the sanctioning organizations would bring back the old gasser classes with NO electronics and NO computers, I know about six guys locally (including me) who would be scrambling to get back into drag racing...