Help with Rear end gear ratio

Not to spoil your day, but that mild 318 will not push that car below 14's. I wish you the best in your build, but be careful to not overtire the car. Like stated above you will more than likely need to regear later for a more substanial build. I would rec'd going to a 26x9 tire and a 4.10 gear. That combo will easily move an A body to low 11's and not have traction problems if you do the rest of the suspension correctly. Just to give you an idea, at 3400lbs race weight you will need approx 480 hp to accomplish mid 11's