I agree with the 3.91's or 4.10's with your 505 and 28" tall tires. As you know I use 4.30's but I have 29" tall tires and they work good with my 440. But you will have gobs of torque and will run good with 3.91's or 4.10's at the most to take advantage of the power band in your stroker. What a nice car you have. Ron