with 275/60's and a prepped track, 1.70's shouldn't be too hard.
Right side airbag at 20 psi, 18 psi in the tires. Tires kept clean (no dirt, dust, crushed rock, grass or marbled rubber after the first burnout of the night) Leave with about 7 psi.
235 BFGs , stock suspension with air bags, see sig.. DR Launch Info
I just pulled the front sway bar off to try and get into the 1.6s. Also have some used 275/60s BFGs, as UNGN mentioned, on the way for my 8.5" Vectors. Also going to box the LCAs and have fixed the DS air bag line kink. I had noticed the car went right , unloaded the rear, and spun the slicks, on a higher 10 lb launch I attempted , and that was maybe part of the reason.
My fastest quarter mph is the same as your 86 T. I am shooting for that low 12/high 11 on a mostly stock car, so most of it will be in the launch. I've only made about 6 passes on the 235 BFGs, the rest was on 28x9 MT Drags.
I've cut a 1.77 on 235/60-15 BFG DR's. 100% stock suspension. Most of my 60fts. are in the low 1.8's over the last 15 passes.
This was heating them to a good smoke (see avatar... ), and launching at ~4-5psi.
You've got some great mph for only 17psi...what other mods on the '86 T?
S.