NO way is he gonna run 12's.
the car would have to be about 2600/2700lbs and have a decant working suspension to run 12.80/90's stock 5spd with slicks.. look at my signature. thats on a stock 5.0 motor and a 150 hit. but my car is really lite. removal of entire heat/ac, power steering swapped to manual rack, electric fan/H2o, fiber glass hood/deck lid, no pass/rear seat, aluminum D/S, no radio/extra wires, trimmed off extra metal( bumper braces etc..) battery in trunk over pass rear wheel,Bottle over drivers rear wheel, Only run a 1/4 tank dude it goes on and on to run a stock 5.0 that fast... whats his timing going to be at???? pull out that spout and run full advanced timing. 26*/28* . set your timing at 16*(spout out) which is 26* (spout in). throw a couple more lbs of fuel pressure at it too.( if you got an AFPR). Sharad if you ran a 12.91 on a stock motor than you know it takes quite a bit to accomplish that. Way more that gears and slicks..
1989 notchback- Z spec t-5,race weight -2700lbs.stock 5.0 long block Nitrous works wetkit 150shot, 390 motive gear,moser 33spline,moser spool,11.32 @ 118MPH. 1.47 60'.