What rear end gears for 904?

With 3.92s and 27" tires;
and with an A904;
3.92x 2.45x 1.1 in the TC = a starter gear of 10.56; and
70=3550@4% slip

But for a streeter, a starter gear of 1056 with an automatic is overkill, because at zero mph, the TC ratio can easily climb to 1.8, so at zero mph, the instantaneous starter ratio is actually;
3.92 x2.45x1.8= 17.29, totally overkill. At this point, you are just giving away cruise rpm for tire smoke.
So you will never be able to use Nos in first gear.
With 3.92s and that 268* cam, top of first is ~48 mph. On the shift, the Rs fall to 3400, which is already nearing max torque, say 380 ftlbs x1.45x3.92x1.2 in the TC =2590 ftlbs, by itself still enough to keep the tires spinning, so kindof a waste to hit the Nos just yet; and the torque is still climbing. By 60 mph, the Rs are back up to 4100 just about peak torque, say 410 ftlbs, so; 410x1.45x3.92x1.2=2563; the tires may have stopped spinning, can't say for sure.
In any case, now you are getting close to hitting the Nos button........ at 60 mph. And when you do, you can expect about 100ftlbs to kick in so;
505x1.45x3.92x1.1=3160 ftlbs out the back, and the tires are probably gonna light up again...... and top of second is coming at 78 mph.
So what's my point?
Well, to my way of thinking, what's the point of Nos on the street, if the motor by itself, can spin the tires to the speed limit? You got too much motor, or too much gear,or I estimated not sticky enough tires; to use Nos below ~60 mph. Gears are easier and cheaper to change.
Or
Just save the Nos for the track.
I guess time will tell.......