Put the tallest tire you can fit. A tall/thin tire has a larger footprint then a short/wide tire.
Any dyno sheet on the motor? What converter ?
Anyway, being chevys like rpm, I am guessing a 4.10 or 4.30 would do it. It is tough, NA likes more gear,N2O less gear.
For suspension do a search using my name.
I got mid to low 1.4 60 foots with the following:
Front stock coils minus one coil, poly rebuild, 3-way shocks
Rear Eibach lowering springs, single adjustible shocks, p/s air bag, adjustible upper and lower contorl arms.
Car would lift the l/f about a foot in the air and the r/r would drop about 6", all twisted up. It was a fun but scary ride.
I added my own rear sway bar and then stepped up to a HR&stuff rear bar and all of the drama went away.
Later ugraded to double adjustible shocks all around and now the car leave straight and true. I can make a run with one hand on the wheel like I am drivin' to church.
On a side note selling the rear and suspension out of the car.
78 Olds Cutlass Drag car PONTIAC powered with 440 (destroked 455), th400, 12bolt with spool 4.10z Best to date firstname.lastname@example.org mph at 3250#
79 Grand Prix, will be new home for the 440 Goal "street Legal" 9.75z@135mph at 2900#
83 Malibu Wagon Crate 350, Custom T5, 8.5 with Auburn posi 3.73z Making it the Ultimate Utility VehicleGo, tow and show (not so much show, yet)