I don't know about 12.50's, there is a guy on CGP running a 2.6" and ~20* timing on his top swap setup and he ran a 12.44 @112 mph. With a full size IC and a 3.0" pulley with that setup I think you would hit 12.80's or 12.90s. Either way traction is going to be a big problem and you need to think about getting at least some DR's.