Gearing ?

Here's an option. Get an OD tranny or a GVOD and run the 4.56 gears. Problem solved.

How much power out of the 318 currently?

Why such a short tire?

You don't want to be shifting right before the finish line.

Here is another thought. A 3.23 gear with 25" tires is about right for cruise RPM on the street. It would also go through the traps at 103MPH@6500RPM in 2nd gear.