Hmmm....3.55s or ???

Like Mike said with a stock 318 I dont think gears will knock a second of your ET, but gearing wont hurt. Id go with as much gear as you can stand on the street. 3.91 or 4.10 are great for street/strip small blocks. But if you do a lot of highway driving you may be better off sticking with the 3.23 or 355s