Bigger tires might help a bit but I think you'll find that 4.88 gears are too much. I started with 4.56 gears in my Duster then went to 4.10 gears and my next change will be to 3.89 gears. A buddy of mine did the same thing with his B body car. He has a 505 with TF270 heads and he is now running 3.89 gears also. He started with 4.56 but was constantly into the rev limiter. He went to 4.10 but still hit the rev limiter at about the 1000 ft mark so now he has the 3.89 gears and can pull hard all the way down the track. He runs 9.70 at 135.
