Stall Speed

[Squirrell]

Hi Guys, I have a 1990 chevy Beretta , 572 ci bbc made 893 hp and 756 ft lb torque. 5400 stall, Car weighs 2350 lbs , 180 first gear and 3.90 rear gear and 32 x 14 Mickey Thompsons. I am having trouble hooking up on a marginal track, my question is if I change the convertor to 4200 or 4500 rpm down from 5400 rpm will it stop the wheel spin on the startline ?.
If I lower the launch rpm will that have a similar effect or will it flash up to 5400 and still spin the tire.
We found our tire guage was incorrect . The tire was 4 psi higher than what the tire gauge read , ie, 7 psi was actually 11 psi. We have seen better results with the tire at 7 psi on a good track but it will spin on a marginal track.
The engine makes 748 ft lbs at 4600 rpm and 756 ft lbs at 5800 rpm , would a convertor with 4200 stall still behave the same as the 5400 convertor due to the fact that the engine has a lot of torque down low.
Can I achieve a softer hit with simply lowering the launch rpm ?. Still learning to set the shocks .
Thanks in advance for your thoughts Patrick.