Gears on street tires will only make your times worse. You will spin more until you can get some traction. Get a set of Drag Radials and some Lower Control Arms at the least. Launch somewhere between 4-4.5k and hold on. Drag radials are a little shorter, so it's like you are adding 3.55's or 3.73's anyway. With the tune, drag radials, and Lower control arms you should be running a 1.8 or better 60' and a low 8 second 8th mile. If you don't ever planning on running 1/4 mile, look at you RPM in the 1/8 when you finish. If you are 6k or below, it would probably be safe to add some gear. Any higher could force another shift, negating the better acceleration off the line. Get an aftermarket shifter as well when $$$ permits. The stock one is crap. You will thank yourself every day if you do. Get a Barton or MGW and you won't be disappointed.
BTW,if you ever wind up running 1/4, 3.73's with drag radials will force you to hiit 5th gear. With my Drag radials and 3.31's I cross the 1/4 stripe around 6500 RPM which is right where you want to be. Any extra acceleration you get out of 3.73's will be lost with the extra shift.