If it were me, rather than cutting the car, I would stick with a 28 tire.
You are currently running the same tire I am.
Few years back I had a much quicker car( 70 Duster) and I ran the Hoosier bias QTP tires. Hooked outstanding even with super stock springs on a 9 sec car.

69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8