215 drag radial traction

I know 12.5 is going to be hard to achieve. I don't remember my 60' times. I have about 3000 stall converter, 3.73 gears. I hold the car at 1800 rpm and then roll on the gas. Just smashing the gas pedal I spin and end up a 13.7 ET. I have only run with a full tank of gas. I'm kinda stuck with weight because its a pretty correct GTS and I don't have it in me to butcher it.

I also want to keep the 3.73 gears since its street driven. I think the way to go would be 235/60r15 rear tires and get it tuned and go from there.