I used to have a 93 Z28 that ran 13.9's in the quarter with a K&N CAI and gear (3:73's). It was an automatic and it Owned most mustangs it ran up against. Just about any year GT, Cobras up to 2001, 5-slows, you name it. When I ran into something a bit over my head. NO PROBLEM! I had a 175 shot of nitrous that brought the quarter down to the low 12's. Hide the noid in the bumper. Run the lines up the CAI and into the throttle body. Better Fuel pump to handle the increase in Fuel. Insulated Gym bag behind the seat with the bottle in it worked well as a bottle heater. Answer: What Nitrous? You Lose!
You can get a 93-95 LT-1 for in the $3000-$4000 range. Add another grand and you can get a LS-1 (98 is the earliest year). They may not sell like the Mustangs but they beat them. Trust me.
My Z was real cheap on insurance for some reason to.