I take it you are meaning an automatic right?
If so yeah a performance rebuild with a loose converter will help tons. A 3500 stall speed would really help you out along with a quality performance rebuild. I picked up .7 second in my Coronet going from a stock rebuilt 727 with a shift kit to a reverse manual valvebody with a 3500 stall, granted its cammed more than a stock stang.
If you are going superccharged you may want to consider a different stall speed though. If you are doing a lot of street driving you also dont want a stall thats too high as it will ruin your low speed driveability.