If I were you, I would post this in the Forums on Yellow Bullet. Much more help there. If you are not a member, sign up, it's worth it.
I don't think changing to a 4.10 gear is the right way to go in the 1/8 mile unless you are running out of RPM or spinning a lot. Since you have an ATI converter, I would confer with them on maybe tuning the converter to your combo. That car should be low 1.40 60 ft.