12's are easy with a stock 340 stroke & heads in a E body 'cuda. i managed 12.8@108 with J heads & a home port job, an old set of jahns forged pistons @ 10.8 cr & a hughes solid cam that was 250@50, an M1 with a stock 750 dp. trans had a TA 3500 verta & the 8 3/4 had 3.9 gears. with more cubes you'll be at the pointy end of the 12's if not high 11's.