Goin V-8

If it is an 8 1/4 and it is 320ish it would be a 3.21, an 8 1/4 will be fine for a low to mid 13's car. According to your rules you can't go any faster than 13 flat but you can go as slow as you want. Even if the car runs in the 15 sec range you will still have fun. My first car ran 15.2's all day long and I had a great time. The key is to be consistent. It can be easier to be consistent with a slower car than a faster car because of possible traction problems with higher HP cars.

Chuck