Lots of variables determine what will work best for your setup (weight, transmission, power, launch rpm, etc). If it's an 1/8 mile car, 4.10 gear or 1/4 mile car, 3.55 gear. This is what my car likes!
IMO, set up the gears like you would a N/A setup. Figure out what rpm you are going to shift at and what rpm you want to go through the traps at with with your tire size. Don't get caught up in the 3.08/2.73 gear to "load" the turbo!!
THIS IS MY FIRST TURBO PROJECT AND IT IS 79 BU, 350 TRANS, 350 TWIN TURBO, STOCK WEIGHT CAR AT THE MOMENT. MY BROTHER WITH A 94 S-10 WITH 383 IS GIVING ME HELL ABOUT IT CALLIN ME SLOW BU, I HAVE TO SET HIM STRAIGHT. HE'S 10.9 ON MOTOR WITH 2 KITS WAITIN